IRIS: Custom Synthesis eBook

CUSTOM SYNTHESIS

Version: IB11_2

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Empowering Peptide Innovation With this guiding theme in mind, Iris Biotech’s mission is to support researchers by supplying • innovative technologies, • rare compounds, • as well as a broad portfolio on standard consumables, available in flexible quantities from small scale to bulk quantities. To fulfill our dedication “Empowering Peptide Innovation”, we are attending various conferences, symposia, and exhibitions each year. This allows us to remain in direct contact with scientists all over the world, both from academia and industry, to exchange knowledge, and to gather new ideas to tackle your current challenges.

Guided by our dedication to provide • competent service, • as well as novel substances and • latest technologies, Iris Biotech is your trusted partner for the world of peptides, while having strong expertise in associated disciplines. Thus, our portfolio comprises reagents and tools for the synthesis and modification of peptides, e.g. amino acids, resins and solvents but also for related technologies such as Drug Delivery, Linkerology® and Life Sciences.

Amino Acids

Building Blocks

Life Sciences

Drug Delivery

Reagents

Resins

Linkerology®

Click Chemistry

Owed to the growing demand for tailor-made compounds, our portfolio is fine-tuned by our Custom Synthesis Service at Iris Biotech Laboratories. Our skilled scientists offer profound expertise in • de novo route development, • upscaling towards larger scale production, • as well as synthesis optimization for increased efficiency.

Examples are the synthesis of rare chiral building blocks, unnatural amino acid derivatives, sophisticated orthogonal protecting groups, heterocycles, building blocks for nucleotides, PEGs and PEG-analogues as well as specific linkers for controlled drug delivery and release.

Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

III

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Portfolio Overview Peptide Synthesis and Modification

Linkerology® and Drug Delivery

(Protected) Amino Acids

Linkers for Solid Phase Peptide Synthesis

Carbohydrates

Cleavable Linkers

Mannose, Xylose and others

Val-Ala based, Val-Cit based,

Drug Metabolites

Standards such as Fmoc-D/L-AAA and Boc-D/L-AAA, Smoc amino acids for peptide synthesis in water, variety of protecting groups (e.g. Pbf, Trt, tBu, Bzl, Acm,

disulfide based, Dde-helping

Life Sciences

Galactose, Glucose, Maltose,

hands

Peptides

Photo-Activatable Linkers

Substrates & Inhibitors

Functionalized Linkers

E.g. protein kinase inhibitors,

Building Blocks

Clickable linkers, trifunctional

Snap/Clip)-tagged proteins

Amino alcohols, amino aldehy-

linkers, linkers with maleimide

Mob, SIT, Phacm, Allocam, Mmt), unusual amino acids, fluorinated derivatives, substituted prolines, arginine analogues

des, diamines and hydrazines, (pseudoproline) dipeptides, polyamines and spermines, fatty acid derivatives Reagents Coupling reagents, solvents and

function, cross-linkers, selective N-term acylation and biotiny-

Dyes and Fluorescent Labels

PROTACs

E.g. ICG, AMC, DAPI

Ligands, linkers & modules

Maillard & Amadori Reaction Products

Fullerenes & Poly(2-oxazolines)

Resins

Poly-Amino Acids

Preloaded resins (e.g. based on

Poly-Arg, Poly-Glu, Poly-Lys,

benzhydryl, Merrifield, PAM, Rink, Wang), scavenger resins, hydrazone resins

Natural Products

lation

scavengers, protecting groups

Trityl, TCP, TentaGel, Methoxy-

substrates for fusion (Halo/

Poly-Orn, Poly-Sar PEGylation Branched PEGylating reagents, (amino-)PEG-acids, PEG-amines & hydrazides & guanidines, reagents for Click-conjugation, Biotin-PEG-reagents, PEG-thiols, PEG-maleimides, other PEGylating reagents

Large portfolio of derivatives useful as standards for food, pharma and cosmetics industry Vitamins

Custom Synthesis Your project requires a compound not listed in our portfolio?

Get in contact and inquire about our custom synthesis capabilities.

Our experienced scientists are excited to accept your synthetic challenge!

In such cases, your request undergoes the following stages:

search Step-by-Step Analysis

Process Evaluation

Strategy Development

Quality Consistency

• Customer’s demands

• Detailed literature review • Synthetic possibilities

• Protocol development • Method development and validation • Customized synthesis

• Identity confirmation • Purity verification

Our Service Promise All our services are based on high standards, transparency & documentation, trust, honesty & confidentiality, as well as the required know-how.

High Standards

Transparency & Documentation

• Values: sustainability & responsibility

• Talk to our specialists – customer care

• State-of-the-art equipment & latest

• Certificates of analysis & impurity profiling

technologies

• Analytical and process reports

• High quality standards • Qualified suppliers & regular audits

Trust, Honesty & Confidentiality

Our Know-How

• Intergenerational business valuing

• One-step reactions & complex

partnerships

multi-step synthesis

• Meeting the customer‘s expectations

• Scalability from mg to kg quantities

• Integrity towards our customers

• Route scouting

Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

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Table of contents

Custom Synthesis 1.

Custom Synthesis at Iris Biotech

1

1.1.

Your Demand

1

1.2.

Our Approach

2

1.3.

Our Locations

2

2. Fields of Custom Synthesis

3

2.1.

Amino Acid Derivatives

3

2.2.

Customized Linkers

19

2.3.

Photoresponsive Derivatives

27

2.4.

Polymers

30

2.5.

Development Projects

38

2.6.

Contract Manufacturing of Lab Samples according to your own Process

39

Code of Conduct

41

Terms and Conditions of Sales

43

Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

VII

Custom Synthesis

1. Custom .

Synthesis at Iris Biotech 1.1. Your Demand You could not find what you are looking for?

Despite offering more than 6,000 different products within our categories

Amino Acids

Building Blocks

Life Sciences

Drug Delivery

Reagents

Resins

Linkerology®

Click Chemistry

your project might require either • a de novo route development, • the synthesis of certain derivatives not listed in our catalogue, • an optimization or re-design of an existing synthetic route for increased efficiency, • the upscaling towards larger scale production, • or the development of a reliable process also suitable for industrial applications.

For custom synthesis, there are types of reactions we carry out routinely like chiral synthesis, enzymatic and other types of optical resolution, as well as hydrogenations under high pressure. We have specific know-how to work with amphiphilic and hydrophilic compounds, which might be difficult to synthesize and purify. Our experienced personnel has profound knowledge in research, process development, production and analytics and strives their hardest to bring your order to fast and efficient completion.

Examples are the synthesis of rare chiral building blocks, unnatural amino acid derivatives, photoresponsive derivatives, sophisticated orthogonal protecting groups, PEGs and polymers for drug delivery

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as well as specific linkers for surface functionalization as well as controlled drug delivery and release.

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You do not only need a single compound but want to outsource a whole project?

You want to bring your ideas one step further but do not have the time, equipment, expertise, or manpower to get started?

You are struggling with one of your projects and don’t know how to continue?

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Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

Inquire about process development at Iris Biotech.

We are pleased to enter a confidentiality (CDA)/non-disclosure (NDA) agreement with you to start your project. We are developing a suitable process for your application: • in-depth literature research • step-by-step analysis • screening of test reactions • frequent customer consultation to report about preliminary results • optimization of reaction conditions to improve crude purity • workup and isolation optimization • identification and quantification of impurities and side-products • investigation of critical process parameters and applicable process parameter ranges • full documentation

1.2. Our Approach All eyes on you and your demands!

Custom synthesis describes the exclusive synthesis of chemical products according to your request and specifications. Based on our experience, we provide profound theoretical and practical know-how and show the required flexibility and creativity to drive your synthetic challenge to success. According to your needs, we figure out a pathway for the synthesis of your derivative of choice – be it a single small-scale synthesis or for frequent large-scale demands.

We stay in dialogue to inform you about the ongoing progress. During your whole project, one project

.

manager will be assigned to you to assure effective and transparent exchange.

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Relying on those principles Iris Biotech is your trusted partner for custom synthesis!

1.3. Our Locations Whereas Iris Biotech is located in Marktredwitz, our main synthesis laboratories are located in the Business and Industry Park Willstätt (www.biw-gmbh.net), a more than forty football fields large technology location in the heart of Europe. The site is operated for more than 50 years. We share the infrastructure with more than 25 companies of different branches and benefit of outstanding expansion possibilities, professional services, and infrastructure, as well as a cost-efficient set-up.

In those laboratories, we have all capabilities to bring your order to fast and efficient completion using state-of-the-art reactors and analytical equipment for process control and the careful characterization of intermediates and end products.

In addition, we are cooperating with around 35 selected contract manufacturers and leading universities worldwide. All our manufacturing partners go through an intensive and detailed supplier qualification program including analysis of raw materials, costs and terms, on time delivery, regular audits, and performance tracking to guarantee quality consistency.

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2

Custom Synthesis

2.

Fields . of Custom Synthesis

2.1. Amino Acid Derivatives One of our major foci is the custom synthesis of unnatural amino acids.

Examples are the synthesis of Cα-methyl and alkyl amino acids, β,β-dimethylated amino acids, Cα-substituted amino acids, homo-β2, homo-β3 and γ-amino acids, as well as fluorinated amino acids and many more.

This structural diversity of derivatives allows for structure-activity relationship investigations. Often, only minor changes in the chemical structure allow to improve chemical stability and overall performance while maintaining or even increasing biological activity.

Fig. 1: Possibilities for amino acid modifications available via custom synthesis.

2.1.1. General Approaches The probably most widely used and first approach to unnatural amino acids proceeds via alkylation of diethyl acetamido malonate. This process is daily routine in our laboratories and provides easy access to a large number of analogues in gram scale. Racemic mixtures of both enantiomers are being produced, which need to be separated by enzymatic methods or other separation technologies.

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O

O

Ac HN

OEt

Base

OEt

- H+

Ac

O OEt

HN

+ R-Br

Ac-HN

OEt

R

OEt

OEt

O

O

O

H+ / H2O - CO2

Racemization O

O H2N

(S)

OH

H N

Ac

(R)

O

Acylase

OH

Ac

H N

R

R

OH- / H2O - CO2

OH R

Racemization O

O Ac

H N

(S)

OH

Ac

H N

(R)

O

Protease

OEt

Ac

H N

R

R

OEt R

Fig. 2: Schematic illustration of the acetamido malonate route.

As drawbacks of this synthetic route, one can consider that • the alkylating reagent is often not commercially available or very costly, • often only one of the two enantiomers is required, the other one is “chiral” waste, which needs to be converted into the target compound via racemization, • available enzymes (acylases and esterases) are not able to separate both isomers.

Typical compounds which are accessible through this process are phenylalanine derivatives and amino acids with certain aliphatic residues carrying additional functional groups.

Another approach for the generation of amino acids is the so-called Strecker-synthesis. It converts aldehydes into α-aminonitriles, which can be hydrolyzed yielding a racemic amino acid bearing one carbon more than the aldehyde educt.

O R

KCN H

NH4Cl

N

H2N

H+/H2O

R

O H2N

OH R

Fig. 3: General mechanism of the Strecker amino acid synthesis.

In case a chiral amine is used in the place of ammonium chloride, chiral induction will yield the preferred enantiomer as the major product. The first example of this approach was reported in 1963 by Harada et al. by using the chrial D-(-)-α-methylbenzylamine. Hydrolysis of the nitrile and subsequent hydrogenation afforded the diastereoselective amino acid product.

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Custom Synthesis

O R

CN

KCN R

H H2N

H2

*

*

H+/H2O N

*

H

O

R

OH *

N

*

H

O H2N

*

OH

R

Fig. 4: Example for the Strecker synthesis upon chiral induction.

References: → Synthetic Amino Acids. Syntheses from Acetamidomalonic Ester; H. R. Snyder, J. F. Shekleton, C. D. Lewis; J. Am. Chem. Soc. 1945; 67(2): 310-312. https://doi.org/10.1021/ja01218a047 → Synthesis of .alpha.-amino acids by alkylation of diethyl acetamidomalonate in the presence of palladium complexes; J. P. Haudegond, Y. Chauvin, D. Commereuc; J. Org. Chem. 1979; 44(17): 3063-3065. https://doi.org/10.1021/jo01331a020 → Asymmetric Strecker Synthesis of α-Amino Acids via a Crystallization-Induced Asymmetric Transformation Using (R)-Phenylglycine as Chiral Auxiliary; W H. J. Boesten, J.-P. G. Seerden, B. de Lange, H. J. A. Dielemans, H. L. M. Elsenberg, B. Kaptein, H. M. Moody, R. M. Kellogg, Q. B. Broxterman; Org. Lett. 2001; 3(8): 1121-1124. https://doi.org/10.1021/ol007042c → Highly Stereoselective Strecker Synthesis Induced by a Slight Modification of Benzhydrylamine from Achiral to Chiral; N. Takamatsu, S. Aiba, T. Yamada, Y. Tokunaga, T. Kawasaki; Chem. Eur. J. 2018; 24(6): 1304-1310. https://doi.org/10.1002/chem.201704033 → Petasis vs. Strecker Amino Acid Synthesis: Convergence, Divergence and Opportunities in Organic Synthesis; W. Masamba; Molecules 2021; 26(6): 1707. https://doi.org/10.3390/molecules26061707 → Asymmetric Synthesis of α-Amino-acids by the Strecker Synthesis; K. Harada; Nature 1963; 4912: 1201. https://doi.org/10.1038/2001201a0 → Asymmetric Strecker Reaction with Chiral Amines: a Catalyst-Free Protocol Using Acetone Cyanohydrin in Water; M. Pori, P. Galletti, R. Soldati, D. Giacomini; Eur. J. Org. Chem. 2013; 9: 1683-1695. https://doi.org/10.1002/ejoc.201201533

2.1.2. Substituted Homo-β- and γ-Amino Acids & Statines The application of peptides as therapeutic agents has significantly increased over the last years bolstered by improvements in peptide manufacturing. Recent commercial successes, e.g. of GLP-1 analogues such as Liraglutide and Semaglutide, encouraged the development of peptides as therapeutic agents and large-scale synthesis of peptide APIs. However, their inherent susceptibility to proteolytic degradation resulting in rapid elimination in vivo has significantly impeded their broader use. Thus, the stability of peptides and especially their half-life during circulation is becoming increasingly important. Structural diversity and stabilization towards chemical and enzymatic degradation are the guiding theme of amino acid derivatization.

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Homologization of natural amino acids results e.g. in homo-β2, homo-β 3 and γ-amino acids. Several platforms are available to display the whole assortment of homo-amino acids, as well as the higher homologues and double substituted derivatives β2,2-, β 3,3-, and corresponding γ-amino acids. Via specific templates with tailored residues each conformation can precisely be addressed. Our platform allows a large variety of substituted γ-amino butyric acid and statine analogues.

O H2N

O H2N

OH

2

R

1

3

O R

OH

R

R

2

2

1

H2N

NH2

2,2-R2-γ-amino acid

R

R R

R

4

4

OH

3

NH2

3,3-R2-γ-amino acid

4,4-R2-γ-amino acid

O

OH

NH2 Statines with any available R

1

2

OH

3

R

1

2

OH

O 1

R

homo-β3

3 4

NH2

2

R

O

1

2

OH

OH

3

O

3

4

1

2

OH

homo-β2

O

R

1

3

H2N

homo (= α3)

normal (= α2)

O

R

R 4

OH

3

NH2 chiral 4-R-γ-amino acid

Fig. 5: Nomenclature for homo-β- and γ-amino acids and statine synthesis.

Those derivatives show superior properties such as: • high structural diversity • superior biological activity • tuning of cell & membrane penetration • improved chemical stability • enhanced enzymatic stability • fine tuning of solubility and lipophilicity • adjusting of the isoelectric point Therefore, homo-β- and γ-amino acids are especially of interest in developing peptide pharmaceuticals.

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Custom Synthesis Our toolbox allows for the synthesis of • homo-β2 amino acids including 2,2-disubstituted analogues • homo-β 3 amino acids including 3,3-disubstituted analogues • double substituted γ-amino acids on the positions 2,2 or 3,3 or 4,4 • chiral 4-substituted γ-amino acids • statine analogues with side chains from any accessible residue β-Disubstituted Amino Acids O H2N

R OH

R

γ-Amino Acids

O

R

H2N

PG

OH

O

H N

R

OH

PG

OH

H N

O OH

R

R

β2,2 Amino Acids O PG-HN

O OH

PG-HN

F

O

O OH

F

PG-HN

OH

PG-HN

O OH

PG-HN

O OH PG-HN

OH

N

O

Boc

β3,3 Amino Acids PG-HN

OH

PG-HN

OH

O

PG-HN

OH

O

PG-HN

OH

PG-HN

OH

O

O O

PG-HN

OH

O S

O N Boc

Statine Analogues

Boc

H N

OH

O OH

Boc

H N

OH

O OH NH

Fig. 6: Structural examples for substituted homo-β- and γ-amino acids and statines.

References: → Amino Acids, Peptides and Proteins in Organic Chemistry. Vol. 1 – Origins and Synthesis of Amino Acids.

Edited by A. B. Hughes; 2011; Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. ISBN: 978-3-527-32096-7; Chapter 13 Synthesis of gamma- and delta-Amino Acids; A. Trabocchini, G. Menchi, A. Guarna; 527-677. → SDZ PRI 053, an orally bioavailable human immunodeficiency virus type 1 proteinase inhibitor containing the 2-aminobenzylstatine moiety; A. Billich, G. Fricker, I. Müller, P. Donatsch, P. Ettmayer, H. Gstach, P. Lehr, P. Peichl, D. Scholz, B. Rosenwirth; Antimicrob Agents Chemother. 1995; 39(7): 1406-13. https://doi.org/10.1128/AAC.39.7.1406 → Design and synthesis of hydroxyethylene-based peptidomimetic inhibitors of human beta-secretase; R. K. Hom, A. F. Gailunas, S. Mamo, L. Y. Fang, J. S. Tung, D. E. Walker, D. Davis, E. D. Thorsett, N. E. Jewett, J. B. Moon, V. John; J Med Chem. 2004; 47(1): 158-64. https://doi.org/10.1021/jm0304008

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Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

→ Molecular basis for selectivity of high affinity peptide antagonists for the gastrin-releasing peptide receptor; K. Tokita, T. Katsuno, S. J. Hocart, D. H. Coy, M. Llinares, J. Martinez, R. T. Jensen; J Biol Chem. 2001; 276(39): 36652-63. https://doi.org/10.1074/jbc.M104566200 → Mechanism of Inhibition of beta-site amyloid precursor protein-cleaving enzyme (BACE) by a statine-based peptide; J. Marcinkeviciene, Y. Luo, N. R. Graciani, A. P. Combs, R. A. Copeland; J Biol Chem. 2001; 276(26): 23790-4. https://doi.org/10.1074/jbc.M101896200

2.1.3. β,β-Dimethylated Amino Acids Another approach for the generation of peptides with superior properties and increased stability is represented by the incorporation of β,β-dimethylated amino acids. Thereby, the structure and conformation of the α-carbon is being maintained, while modification occurs at the neighboring carbon.

It is reported that the incorporation of β,β-amino acid analogues at the P 1’ position, directly C-termi-

nal of the enzyme cleavage site, is rendering peptides highly resistant to serine protease degradation without significantly impacting their biological activity or secondary structure, as shown by circular dichroism and receptor activation in comparison to their “original” counterparts. This includes stability towards dipeptidyl peptidase IV (DPP IV), dipeptidyl peptidase 8 (DPP 8), fibroblast activation protein alpha (FAP alpha), alpha-lytic protease (alpha LP), trypsin, and chymotrypsin. Comparative hydrolysis studies of hexapeptides carrying either the natural amino acid residues Leu or Ile at the P 1’ position or the β,β-dimethylated derivative showed that already after 30 min, more than 70% of AP(Leu)SWS and AP(Ile)SWS

were hydrolyzed whereas the modified sequence was completely resistant to DPP IV-mediated cleavage during that time.

Fmoc

Fmoc

O

H N

OH

Fmoc

N OH

N

OH

OH

Fmoc

OH NH HN

Fmoc

Fmoc

H N

Ser, Thr

CO2tBu

Fmoc

H N

OH

O OH

NHBoc

Fmoc

H N

O

Trp

Phe

Met

O

OH

OH

N H

His Lys, Orn

H N

Me

Glu

OH

Fmoc

Me

Asp

Fmoc

O

H N

O

H N

OH

O

CO2tBu

Pro Tyr

O

H N

Ile

Arg

NHPbf

OH

O

Fmoc

O

H N

O

Fmoc

O

H N

Fmoc

O

H N

O

Fmoc

H N

O OH

OH

N N

OH

SMe

Fmoc

H N

Trt

O OH

NHBoc

Fig. 7: Examples of β,β-dimethyl amino acid derivatives accessible by Iris Biotech.

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Custom Synthesis References: → A General Method for Making Peptide Therapeutics Resistant to Serine Protease Degradation: Application to Dipeptidyl Peptidase IV Substrates; K. R. Heard, W. Wu, Y. Li, P. Zhao, I. Woznica, J. H. Lai, M. Beinborn, D. G. Sanford, M. T. Dimare, A. K. Chiluwal, D. E. Peters, D. Whicher, J. L. Sudmeier, W. W. Bachovchin; J. Med. Chem. 2013; 56(21): 8339-8351. https://doi.org/10.1021/jm400423p → Synthesis and Biological Activity of Analogues of the Antimicrotubule Agent N-beta,beta-Trimethyl-Lphenylalanyl-N1-[(1S,2E)-3-carboxy-1-isopropylbut-2-enyl]-N1,3-dimethyl-L-valinamide (HTI-286); A. Zask, G. Birnberg, K. Cheung, J. Kaplan, C. Niu, E. Norton, R. Suayan, A. Yamashita, D. Cole, Z. Tang, G. Krishnamurthy, R. Williamson, G. Khafizova, S. Musto, R. Hernandez, T. Annable, X. Yang, C. Discafani, C. Beyer, L. M. Greenberger, F. Loganzo, S. Ayral-Kaloustian; J. Med. Chem. 2004; 47: 4774-4786. https://doi.org/10.1021/jm040056u → Total synthesis of the large non-ribosomal peptide polytheonamide B; M. Inoue, N. Shinohara, S. Tanabe, T. Takahashi, K. Okura, H. Itoh, Y. Mizoguchi, M. Iida, N. Lee; S. Matsuoka; Nat. Chem. 2010; 2: 280-285. https://doi.org/10.1038/nchem.554

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.

Interested in our available catalogue products?

See our flyer on β,β-dimethyl amino acids!

Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

2.1.4. Fluorinated Amino Acids The development of new peptide drugs is often hampered by limited affinity, stability, and rapid digestion by human proteases. The introduction of non-proteinogenic amino acids with derivatized side-chain functionalities is reported as a powerful tool to improve kinetic and thermodynamic properties of the respective peptides as well as to increase proteolytic and structural stability.

Besides the above-mentioned approaches of using homo-β- and γ-amino acids or β,β-dimethylated amino acids, fluorinated building blocks represent another tool for scientists within this context. The modification of amino acids with fluorine for enhanced metabolic stability and increased lipophilicity has gained widespread attention dating back to the 1950s, when J. Fried and J. Sabo reported the first fluorine-containing drug fludrocortisone.

Fluorine Properties:

O H2N

• Highest electronegativity of all elements

HO

• High polarity

OH CF3

Fig. 8: High electronegativity of fluorine and impact on the dipole moment of trifluoromethylated amino acids.

The unique property of fluorine, i.e. bearing the highest electronegativity of all elements, oozes out to neighboring groups resulting in unique properties of polarity, lipophilicity, acidity/basicity and conformation of the specific side chains and alters properties on stability, folding kinetics and activity of peptides and proteins.

As ultimate consequence α-amino functions in α-trifluoromethyl amino acids or hydroxy functions in corresponding serines do normally not have to be protected during standard SPPS protocols. Due to the high electron withdrawing property of the α-trifluoromethylgroup their nucleophilicity has been drastically reduced to a level, that acylation will not occur. The drawback is that for forming an amide bond more aggressive acetylating methodologies have to be applied. It is most convenient in such cases to use a dipeptide building block consisting of a normal Fmoc-protected amino acids coupled to the fluorinated building block.

Characteristics: • C–F bond is characterized by high dipole moment + hydrophobic character • low nucleophilicity of neighboring amino and hydroxy groups • no protection in standard SPPS required • increased sterical demand of CF 3 compared to CH3 favors cis-amide bond and induces the formation of β-turns; especially beneficial for the synthesis of cyclic peptides

• improved pharmacokinetics + increased stability towards degradation by proteases • enhanced lipophilicity; thus higher affinity to lipid membranes and stronger interactions with receptors • label for 19F NMR spectroscopy

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Custom Synthesis O F3C

(R)

O

O

(S)

N

F3C

HN O

O

(S)

(R)

N

HN

O cis-amide

trans-amide

steric and electrostatic reasons for cis-amide Fig. 9: CF3 incorporation leads to favored cis-amide formation.

At Iris Biotech, we are offering: • α-trifluoromethyl amino acids • trifluoromethyl substituted amino acids • γ,γ-difluoro amino acids

Trifluoromethyl can be attached to aromatic rings of Phe, Trp and Tyr, added to functional groups like thiol, hydroxyl or amine or be formed by replacing hydrogen in methyl groups.

Fmoc

Fmoc

Fmoc

H N

Fmoc

OH CF3

OH CF3

O

H N

CF3 Fmoc

CH3

OH

O

O

Leu

CF3

Leu

O

H N

OH S-CF3

Met

OH

Phe

H N

F3C

O

Pro CF3

N H Fmoc

Fmoc

Thr

Trp

N O

F3C

OH

Fmoc

Fmoc

H N

O

N O

O OH O CF3

OH

Fig. 10: Examples for trifluoromethyl-substituted amino acid derivatives.

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H N

H3C

Ser

Hyp

O OH S-CF3

Cys

CF3

OH

H N

Fmoc

Tyr

CF3

Fmoc

O

H N

O

H N

Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

O OH O CF3

Besides trifluoromethyl-substituted amino acid derivatives, Iris Biotech is also offering γ,γ -difluoro amino acids. Whereas fluorination on the β-position might lead to racemization on the α-position, even double substitution on the γ-position results in derivatives, which maintain their optical configuration.

Below, please find an exemplary excerpt of our portfolio of fluorinated amino acids. Almost endless combinations are available or can be synthesized based on your custom inquiry.

Fmoc

Fmoc

O

H N

F Fmoc

H N

Fmoc

H N

O OH F F

H2N

OH F F

Fmoc

OH F F

O

O

Gln

Abu

Glu

OH F F

O

H N

O

O

H

H N

Abu

F F

Fmoc

H N

OH F F CH3

NH-Boc Orn

Pro

F

Fmoc

N O

Fmoc

Arg

Fmoc

F

OH F F

Lys

Ape O

O

H N

O

NH HN

N H

O OH F F NH-Boc

OH F F

OH

H N

Pbf

Fig. 11: Examples for γ,γ-difluoro-substituted amino acid derivatives.

References: → Fluorine in Peptide Design and Protein Engineering; C. Jäckel and B. Koksch; Eur J. Org. Chem. 2005; 21: 4483-4503. https://doi.org/10.1002/ejoc.200500205 → Conformational properties of peptides incorporating a fluorinated pseudoproline residue; G. Chaume, D. Feytens, G. Chassaing, S. Lavielle, T. Brigaud, E. Miclet; New J. Chem. 2013; 37: 1336-1342. https://doi.org/10.1039/C3NJ41084F → Impact of fluorination on proteolytic stability of peptides in human blood plasma; V. Asante, J. Mortier, H. Schlüter, B. Koksch; Bioorg. Med. Chem. 2013; 21: 3542-3546. https://doi.org/10.1016/j.bmc.2013.03.051 → Fluorinated Proteins: From Design and Synthesis to Structure and Stability; E. N. G. Marsh; Acc. Chem. Res. 2014; 47: 2878-2886. https://doi.org/10.1021/ar500125m → How Cα-Fluoroalkyl Amino Acids and Peptides Interact with Enzymes: Studies Concerning the Influence on Proteolytic Stability, Enzymatic Resolution and Peptide Coupling; R. Smits, B. Koksch; Curr Top Med Chem 2006; 6: 1483-1498. https://doi.org/10.2174/156802606777951055 → Approaches to Obtaining Fluorinated a-Amino Acids; J. Moschner, V. Stulberg, R. Fernandes, S. Huhmann, J. Leppkes, B. Koksch; Chem. Rev. 2019; 119: 10718-10801. https://doi.org/10.1021/acs.chemrev.9b00024

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Custom Synthesis → Applications of fluorine-containing amino acids for drug design; H. Mei, J. Han, K. D. Klika, K. Izawa, T. Sato, N. A. Meanwell, V. A. Soloshonok; Eur. J. Med. Chem. 2020; 186: 111826. https://doi.org/10.1016/j.ejmech.2019.111826 → Fluorinated amino acids: compatibility with native protein structures and effects on protein-protein interactions; M. Salwiczek, E. K. Nyakatura, U. I. M. Gerling, S. Ye, B. Koksch; Chem. Soc. Rev. 2012; 41: 2135-2171. https://doi.org/10.1039/C1CS15241F → Substitution Effect of the Trifluoromethyl Group on the Bioactivity in Medicinal Chemistry: Statistical Analysis and Energy Calculations; A. Abula, Z. Xu, Z. Zhu, C. Peng, Z. Chen, W. Zhu, H. A. Aisa; J. Chem. Inf. Model 2020; https://doi.org/10.1021/acs.jcim.0c00898 → Synthesis of an MIF-1 analogue containing enantiopure (S)-alpha-trifluoromethyl-proline and biological evaluation on nociception; I. Jlalia, N. Lensen, G. Chaume, E. Dzhambazova, L. Astasidi, R. Hadjiolova, A. Bocheva and T. Brigaud; Eur J Med Chem 2013; 62: 122-9. https://doi.org/10.1016/j.ejmech.2012.12.041

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Interested in our available catalogue products?

See our flyer on trifluoromethyland other fluoro-amino acids.

2.1.5. Arginine Analogues Arginine is characterized by its amphiphilic side chain, with a C 3 alkyl chain terminated by a positively

charged guanidino group. Since the latter can undergo hydrogen bonding as well as ionic interactions with binding partners, Arginine residues are frequently involved in cellular recognition processes.

However, natural proteases and endopeptidases such as Trypsin often cleave peptide chains and proteins predominantly at the carboxyl side of the amino acids Lys and Arg (except when followed by Pro) – one drawback limiting the activity and bioavailability of peptide drugs resulting in unfavorable pharmacokinetics.

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Consequently, derivatives of arginine are highly sought after, be it for the introduction of Arg-mimetics to improve pharmacokinetic properties of therapeutic peptides, or to introduce an Arg derivative suitable for site-selective modification. Iris Biotech offers shorter arginine homologues, which have been shown to increase a peptide’s stability towards tryptic digestion. Similar effects have been observed whenever the guanidine side chain has been modified. Our platform gives access to guanidine substituted arginine derived from any amine, that is commercially accessible.

H2N

NH2

H2N

Fmoc

H N

O (S)

Fmoc

OH N N H

H N

O (S)

Pbf

NH2

HN

OH N N H

Pbf

N H

H2N R

H2N O H2N

H2N

H2N

O

n

N3

NH O O

Fig. 12: Selection of derivatives of arginine accessible through our synthetic approach.

References → Nω-Carbamoylation of the Argininamide Moiety: An Avenue to Insurmountable NPY Y1 Receptor Antagonists and a Radiolabeled Selective High-Affinity Molecular Tool ([3H]UR-MK299) with Extended Residence Time; M. Keller, S. Weiss, C. Hutzler, K. K. Kuhn, C. Mollereau, S. Dukorn, L. Schindler, G. Bernhardt, B. König, A. Buschauer; J. Med. Chem. 2015; 58: 8834-8849. https://doi.org/10.1021/acs.jmedchem.5b00925 → Mimicking of Arginine by Functionalized Nω-Carbamoylated Arginine As a New Broadly Applicable Approach to Labeled Bioactive Peptides: High Affinity Angiotensin, Neuropeptide Y, Neuropeptide FF, and Neurotensin Receptor Ligands As Examples; M. Keller, K. K. Kuhn, J. Einsiedel, H. Hübner, S. Biselli, C. Mollereau, D. Wifling, J. Svobodová, G. Bernhardt, C. Cabrele, P. M. L. Vanderheyden, P. Gmeiner, A. Buschauer; J. Med. Chem. 2016; 59: 1925-1945. https://doi.org/10.1021/acs.jmedchem.5b01495 → Fluorescence Labeling of Neurotensin(8-13) via Arginine Residues Gives Molecular Tools with High Receptor Affinity; M. Keller, S. A. Mahuroof, V. Hong Yee, J. Carpenter, L. Schindler, T. Littmann, A. Pegoli, H. Hubner, G. Bernhardt, P. Gmeiner, N. D. Holliday; ACS Med Chem Lett 2020; 11: 16-22. https://doi.org/10.1021/acsmedchemlett.9b00462 → Shorter Arginine homologues to stabilize peptides towards tryptic digestion; P. Henklein, T. Bruckdorfer; Chem. Today 2008; 6(6): 12-15. → Short arginine analogs: peptide synthesis and prediction of biological effects – efficient synthesis of peptides containing short analogs of arginine and stability evaluation with docking. Prediction of biological effects of short arginine analogs using computational methods; T. A. Dzimbova, P. Henklein, T. Bruckdorfer, R. M. Maier, M. W. Weishaupt, T. I. Pajpanova; Chimica oggi 2019; 37: 28.

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Custom Synthesis → Extended Residence Time; M. Keller, S. Weiss, C. Hutzler, K. K. Kuhn, C. Mollereau, S. Dukorn, L. Schindler, G. Bernhardt, B. Koenig, A. Buschauer; J. Med. Chem. 2015; 58: 8834-49. https://doi.org/10.1021/acs.jmedchem.5b00925 → Substitution of Arginine with Proline and Proline Derivatives in Melanocyte-Stimulating Hormones Leads to Selectivity for Human Melanocortin 4 Receptor; H. Qu, M. Cai, A. V. Mayorov, P. Grieco, M. Zingsheim, D. Trivedi, V. J. Hruby; J. Med. Chem. 2009; 52(12): 3627-3635. https://doi.org/10.1021/jm801300c → Synthesis of Proteins Containing Modified Arginine Residues; A. K. Choudhury, S. Y. Golovine, L. M. Dedkova, S. M. Hecht; Biochem. 2007; 46(13): 406-4076. https://doi.org/10.1021/bi062042r → Practical and Efficient Synthesis of Orthogonally Protected Constrained 4-Guanidinoprolines; M. Tamaki, G. Han, V. J. Hruby; J. Org. Chem. 2001; 66(3): 1038-1042. https://doi.org/10.1021/jo005626m → Conformationally restricted arginine analogs; T. R. Webb, C. Eigenbrot; J. Org. Chem. 1991; 56(9): 3009-3016. https://doi.org/10.1021/jo00009a016

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For inspiration and more information on short arginines and substituted arginines see our flyer on arginine homologues and building blocks.

2.1.6. Substitution around the Proline Scaffold Prolines are key elements frequently positioned at the edge of β-turns in peptides. With modified prolines these positions can be used for filling hydrophobic pockets or to increase hydrophobic interactions, whenever the pyrrolidine ring is substituted with groups like methyl or phenyl.

Furthermore, the cyclic amino acid proline (Pro) represents unique features in terms of its conformational properties as its incorporation into peptide sequences leads to an equilibrium mixture of approximately isoenergetic cis and trans conformers at AAA-Pro bonds, whereas peptide bonds of secondary amino acid amides adopt predominantly the trans C alpha/C alpha conformation.

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Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

R

R

H N

N

O O

N

H

H N

N

O

O

N

H

O

trans

O

cis

Fig. 13: Cis and trans conformation of an AAA-Pro bond.

As many biological cascades are driven by the cis-trans isomerization process of a peptidic ligand within its binding pocket, the analysis of the bioactive conformation – whether cis or trans – represents a versatile strategy to improve a drug’s affinity, its binding properties, and activity.

To analyze the role of both proline isomers separately, substituted proline derivatives can be inserted to lock the AAA-Pro peptide bond either in cis or trans. As reported in the literature, rigid bicylic 2,4-methanoprolines adopt preferably the trans amide conformation and are thus behaving more like primary alpha-amino acids, whereas 5,5-dimethylprolines (Dmp) lock the cis conformation.

H N N R

H N N

O O

NH Methonoproline locks trans

O R

O HN

Dimethylproline locks cis

Fig. 14: The use of methanoprolines and dimethylprolines as conformational amide locks.

Iris Biotech offers a broad variety of substituted prolines with various functional groups. Besides the above mentioned, also fluorinated derivatives, thio-derivatives, amino- as well as azido-prolines are accessible. Functionalization is available at various positions. Just let us know which derivative you are

.

looking for!

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For more information on our available proline catalogue products, please see our flyer on (pseudo-)prolines and derivatives thereof.

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Custom Synthesis References: → N-alpha-Benzoyl-Cis-4-Amino-L-Proline: A gamma-Turn Mimetic; T. P. Curran, N. M. Chandler, R. J. Kennedy, M. T. Keaney; Tetrahedron Lett 1996; 37(12): 1933-1936. https://doi.org/10.1016/0040-4039(96)00307-3 → The cis-4-Amino-L-proline Residue as a Scaffold for the Synthesis of Cyclic and Linear Endomorphin-2 Analogues; A. Mollica, F. Pinnen, A. Stefanucci, F. Feliciani, C. Campestre, L. Mannina, A. P. Sobolev, G. Lucente, P. Davis, J. Lai, S.-W. Ma, F. Porreca, V. J. Hruby; J. Med. Chem. 2012; 55: 3027−3035. https://doi.org/10.1021/jm201402v → Substitution of Arginine with Proline and Proline Derivatives in Melanocyte-Stimulating Hormones Leads to Selectivity for Human Melanocortin 4 Receptor; H. Qu, M. Cai, A. V. Mayorov, P. Grieco, M. Zingsheim, D. Trivedi, V. J. Hruby; J. Med. Chem. 2009; 52(12): 3627-3635. https://doi.org/10.1021/jm801300c → Rational Design of a-Conotoxin Analogues Targeting a7 Nicotinic Acetylcholine Receptors; C. Armishaw, A. A. Jensen, T. Balle, R. J. Clark, K. Harpsøe, C. Skonberg, T. Liljefors, K. Strømgaard; J. Biol. Chem. 2009; 284(14): 9498-9512. https://doi.org/10.1074/jbc.M806136200 → Synthesis of Proteins Containing Modified Arginine Residues; A. K. Choudhury, S. Y. Golovine, L. M. Dedkova, S. M. Hecht; Biochem. 2007; 46(13): 406-4076. https://doi.org/10.1021/bi062042r → Practical and Efficient Synthesis of Orthogonally Protected Constrained 4-Guanidinoprolines; M. Tamaki, G. Han, V. J. Hruby; J. Org. Chem. 2001; 66(3): 1038-1042. https://doi.org/10.1021/jo005626m → Synthesis of Alanine and Proline Amino Acids with Amino or Guanidinium Substitution on the Side Chain; Z. Zhang, A. V. Aerschot, C. Hendrix, R. Busson, F. David, P. Sandra, P. Herdewijn; Tetrahedron 2000; 56(16): 2513-2522. https://doi.org/10.1016/S0040-4020(00)00123-X → Conformationally restricted arginine analogs; T. R. Webb, C. Eigenbrot; J. Org. Chem. 1991; 56(9): 3009-3016. https://doi.org/10.1021/jo00009a016 → Escaping from Flatland: Substituted Bridged Pyrrolidine Fragments with Inherent Three-Dimensional Character; B. Cox, V. Zdorichenko, P. B. Cox, K. I. Booker-Milburn, R. Paumier, L. D. Elliott, M. Robertson-Ralph, G. Bloomfield; ACS Med. Chem. Lett. 2020; 11: 1185-1190. https://doi.org/10.1021/acsmedchemlett.0c00039 → A Peptidyl-Prolyl Model Study: How Does the Electronic Effect Influence the Amide Bond Conformation?

P. K. Mykhailiuk, V. Kubyshkin, T. Bach, N. Budisa; J. Org. Chem. 2017; 82: 8831-8841. https://doi.org/10.1021/acs.joc.7b00803 → Bradykinin and angiotensin II analogs containing a conformationally constrained proline analog; P. Juvvadi, D. J. Dooley, C. C. Humblet, G. H. Lu, E. A. Lunney, R. L. Panek, R. Skeean, G. A. Marshall; Int. J. Pept. Prot. Res. 1992; 40: 163-170. https://doi.org/10.1111/j.1399-3011.1992.tb00289.x → Conformational Properties of 2,4-Methanoproline (2-Carboxy-2,4-methanopyrrolidine) in Peptides: Evidence for 2,4-Methanopyrrolidine Asymmetry Based on Solid-State X-ray Crystallography, 1H NMR in Aqueous Solution, and CNDO/2 Conformational Energy Calculations; S. Talluri, G. T. Montelione, G. van Duyne, L. Piela, J. Clardy, H. A. Scheraga; J. Am. Chem. Soc. 1987; 109: 4473-4477. https://doi.org/10.1021/ja00249a008 → Conformational Properties of 2,4-Methanoproline (2-Carboxy-2,4-methanopyrrolidine) in Peptides: Determination of Preferred Peptide Bond Conformation in Aqueous Solution by Proton Overhauser Measurements; G. T. Montelione, P. Hughes, J. Clardy, H. A. Scheraga; J. Am. Chem. Soc. 1986; 108: 6765-6773. https://doi.org/10.1021/ja00281a051 → Potential Nicotinic Acetylcholine Receptor Ligands from 2,4-Metanoproline Derivatives; A. B. Patel, J. R. Malpass; J. Med. Chem. 2008; 51(21): 7005-7009. https://doi.org/10.1021/jm800537a → Modification of 1-Substituents in the 2-Azabicyclo[2.1.1]hexane Ring System; Approach to Potential Nicotinic Acetylcholine Receptor Ligands from 2,4-Methanoproline Derivatives; J. R. Malpass, A. B. Patel, J. W. Davies, S. Y. Fulford; J. Org. Chem. 2008; 68(24): 9348-9355. https://doi.org/10.1021/jo035199n → A convenient incorporation of conformationally constained 5,5-dimethylproline into the ribonuclease A 89-124 sequence by condensation of synthetic peptide fragments; V. Cerovský, E. Welker, H. A. Scheraga; J. Pept. Res. 2003; 61(3): 140-151. https://doi.org/10.1034/j.1399-3011.2003.00041.x → 5,5-Dimethylproline dipeptides: an acid-stable class of pseudoproline; B. J. van Lierop, W. R. Jackson, A. J. Robinson; Tetrahedron 2010; 66(29): 5357-5366. https://doi.org/10.1016/j.tet.2010.05.068

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2.1.7. Fatty Amino Acids Fatty acids are key components and abundant constituents of all biological systems and are subject of many clinical, nutritional, and metabolic studies as they play a crucial role for normal functioning at all levels of an organism.

Besides this, fatty acids gained interest as the modification of peptides with fatty acids may lead to increased serum half-life and improved pharmacokinetic and pharmacologic in vivo performance via binding to albumin. The most prominent examples in this context are the marketed glucagon-like peptide-1 analogue blockbuster drugs Liraglutide and Semaglutide.

In addition, fatty acid substitution may increase cell permeability of compounds and even allow substances to cross the blood-brain barrier.

The commercial availability of related products facilitates research and allows to gain better understanding and accelerates the development of new medicines.

We provide: • Boc- and Fmoc-protected fatty acids • Functionalized fatty acid derivatives (e.g. NHS active esters, azides, alkynes) • Fatty amino acids

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For more information on available catalogue products related to fatty amino acids and lipidated building blocks, please see our flyer on peptide modifiers.

For any other derivative, please inquire for a custom synthesis!

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Custom Synthesis References: → The ABC of Insulin: The Organic Chemistry of a Small Protein; K. J. Jensen, M. Ostergaard, N. M. Kumar; Chemistry 2020; n/a. https://doi.org/10.1002/chem.202000337 → Harnessing albumin as a carrier for cancer therapies; E. N. Hoogenboezem, C. L. Duvall; Adv Drug Deliv Rev 2018; 130: 73-89. https://doi.org/10.1016/j.addr.2018.07.011 → Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide; J. Lau, P. Bloch, L. Schaffer, I. Pettersson, J. Spetzler, J. Kofoed, K. Madsen, L. B. Knudsen, J. McGuire, D. B. Steensgaard, H. M. Strauss, D. X. Gram, S. M. Knudsen, F. S. Nielsen, P. Thygesen, S. Reedtz-Runge, T. Kruse; J Med Chem 2015; 58: 7370-80. https://doi.org/10.1021/acs.jmedchem.5b00726 → Albumin as fatty acid transporter; G. J. van der Vusse; Drug Metab Pharmacokinet 2009; 24: 300-7. https://doi.org/10.2133/dmpk.24.300 → The Discovery and Development of Liraglutide and Semaglutide; L. B. Knudsen; J. Lau; Front Endocrinol (Lausanne) 2019; 10: 155. https://doi.org/10.3389/fendo.2019.00155 → Synthetic peptide API manufacturing: A mini review of current perspectives for peptide manufacturing; J. H. Rasmussen; Bioorg. Med. Chem. 2018; 26(10): 2914-2918. https://doi.org/10.1016/j.bmc.2018.01.018 → Peptide Half-Life Extension: Divalent, Small-Molecule Albumin Interactions Direct the Systemic Properties of Glucagon-Like Peptide-1 (GLP-1) Analogues; E. M. Bech, M. C. Martos-Maldonado, P. Wismann, K. K. Sørensen, S. B. van Witteloostuijn, M. B. Thygesen, N. Vrang, J. Jelsing, S. L. Pedersen, K. J. Jensen; J. Med. Chem. 2017; 60(17): 7434-7446. https://doi.org/10.1021/acs.jmedchem.7b00787 → The Human GLP-1 Analogs Liraglutide and Semaglutide: Absence of Histopathological Effects on the Pancreas in Nonhuman Primates; C. F. Gotfredsen, A.-M. Mølck, I. Thorup, N. C. B. Nyborg, Z. Salanti, L. B. Knudsen, M. O. Larsen; Diabetes 2014; 63: 2486-2497. https://doi.org/10.2337/db13-1087 → Synthesis of Lipidated Peptides; F. Rosi, G. Triola; Peptide Synthesis and Applications 2013; 161-189. https://doi.org/10.1007/978-1-62703-544-6_12 → New method for quicker and simpler production of lipidated proteins; Granz University of Technology; Science Daily 2019. www.sciencedaily.com/releases/2019/10/191015092245.htm → Synthetic lipidation of peptides and amino acids: monolayer structure and properties; P. Berndt, G. B. Fields, M. Tirrell; J. Am. Chem. Soc. 1995; 117(37): 9515-9522. https://doi.org/10.1021/ja00142a019 → Peptide Lipidation – A Synthetic Strategy to Afford Peptide Based Therapeutics; R. Kowalczyk, P. W. R. Harris, G. M. Williams, S.-H. Yang, M. A. Brimble; Peptides and Peptide-based Biomaterials and their Biomedical Applications 2017; 1030: 185-227. https://doi.org/10.1007/978-3-319-66095-0_9 → Solid-Phase Synthesis of Lipidated Peptides; G. Kragol, M. Lumbierres, J. M. Palomo; H. Waldmann; Angew. Chem. Int. Ed. 2004; 116(43): 5963-5966. https://doi.org/10.1002/ange.200461150

2.2. Customized Linkers Linkerology® at Iris Biotech - we are your experts for Linker Technologies.

Even though certain payloads can directly be attached to their carrier via their functional groups, linkers represent versatile tools for highly efficient conjugation and equip the construct with additional benefits.

2.2.1. General Information A well-chosen and designed linker as connective handle may allow to increase overall solubility, improve stability thus preventing premature payload release, and facilitate the release of the active payload at its target site.

Thus, conjugating highly potent small molecules to vastly target specific biomolecules, such as antibodies, via a selected linker has become a frequently used strategy, particularly in the field of cancer therapy, enlarging the therapeutic window, thus increasing the amount of dosed drug reaching the target cell.

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Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

The variations of linkers are endless and our portfolio only displays a selection out of the whole panoply. Depending on the desired application and conjugation partners, linker design often becomes a rather complex and specific project as many parameters define the final properties. Especially in the field of antibody-drug conjugates (ADCs), the design of the linker is essential as it impacts the efficacy and tolerability of ADCs. In those cases, the linker needs to provide sufficient stability during systemic circulation while providing rapid and efficient release of the cytotoxic drug in its active state inside the tumor cells.

The type of linkage between payload and carrier can basically either be permanent or cleavable under certain well-defined circumstances.

Conjugation to various functional groups, e.g. amines, alcohols, carboxylic acids, thiols can be considered.

Within the following, we are focusing on linker attachment to amines and alcohols and demonstrate a few examples with their specific properties.

2.2.2. Conjugation to Amines Amines are frequently represented functional groups in drugs and active molecules. As an example, the figure below shows prominent drugs bearing a primary, secondary, or tertiary amine.

O H2N N

N

O

O

N NC

HO

O OH

P

NH

O N H

Remdesivir (Veklury)

O O

H N

N H

O

O

O

HO

N

N O

O

Monomethyl auristatin E (MMAE)

O O OH

N H2

Propafenone

Fig. 15: Chemical structures of prominent drugs bearing a primary/secondary/tertiary amine.

The design of the linker already needs to take into account the final cleavage of the payload. Its release can be accelerated by implementation of moieties which fragmentize under certain conditions. One of the most commonly used spacers is the bifunctional para-aminobenzyl alcohol group, which is linked to the linker through an amino group forming an amide bond, while amine-containing payloads are then attached through carbamate functionalities to the benzylic hydroxyl group of the linker. Besides this, linkers are often combined with para-nitrophenol (PNP) as activating motive. Coupling of the payload

.

amine to the linker can easily be monitored visually upon cleavage and release of PNP.

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In the following, we are presenting examples of linkers, which can be used for the conjugation to primary and secondary amines.

Peptidic linkers, e.g. Val-Ala, Val-Cit, Val-Ala-PAB-PNP, Val-Cit-PAB-PNP. The peptide-based linkers Val-Cit and Val-Ala are efficiently cleaved by lysosomal proteases and benefit from increased serum stability and effective payload-release in the targeted cells. First-generation peptide linkers include tetrapeptides such as Gly-Phe-Leu-Gly and Ala-Leu-Ala-Leu, which showed relatively slow drug release and a tendency for aggregation upon payload coupling. These limitations were circumvented by the development and intense investigation of dipeptide linkers.

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Custom Synthesis

O

H N

R N H

O

H N

PAB: requires activation

H N O

R N H

OH

H2N

H N

O

R N H

H N O

PAB-PNP: no activation required

H N O

O

H N

O O

O O

NO2

Ala: R = CH3 Cit: R = (CH2)3-NH(CO)-NH2

Fig: 16: Attachment of a peptidic linker to a primary amine functionalized payload.

References: → Antibody Drug Conjugates: Design and Selection of Linker, Payload and Conjugation Chemistry; J. R. McCombs, S. C. Owen; AAPS J. 2015; 17(2): 339-351. https://doi.org/10.1208/s12248-014-9710-8 → Cathepsin B-labile dipeptide linkers for lysosomal release of doxorubicin from internalizing immunoconjugates: model studies of enzymatic drug release and antigen-specific in vitro anticancer activity.

G. M. Dubowchik, R. A. Firestone, L. Padilla, D. Willner, S. J. Hofstead, K. Mosure, J. O. Knipe, S. J. Lasch, P. A. Trail; Bioconjugate Chem. 2002; 13(4): 855-869. https://doi.org/10.1021/bc025536j → Antibody-drug conjugates: Recent advances in linker chemistry; Z. Su, D. Xiao, F. Xie, L. Liu, Y. Wang, S. Fan, X. Zhou, S. Li; Acta Pharm. Sinica B 2021; https://doi.org/10.1016/j.apsb.2021.03.042 → Optimizing Lysosomal Activation of Antibody-Drug Conjugates (ADCs) by Incorporation of Novel Cleavable Dipeptide Linkers; P. L. Salomon, E. E. Reid, K. E. Archer, L. Harris, E. K. Maloney, A. J. Wilhelm, M. L. Miller, R. V. J. Chari, T. A. Keating, R. Singh; Mol. Pharmaceutics 2019; 16(12): 4817-4825. https://doi.org/10.1021/acs.molpharmaceut.9b00696 → Cleavable linkers in antibody-drug conjugates; J. D. Bargh, A. Isidro-Llobet, J. S. Parker, D. R. Spring; Chem.

Soc. Rev. 2019; 48: 4361-4374. https://doi.org/10.1039/C8CS00676H

Disulfide-based linkers can be used for to the conjugation to amine-containing payloads. Disulfides are stable at physiological pH and are designed to release the drug upon internalization inside cells. The cytosol provides a significantly more reducing environment compared to the extracellular milieu and the presence of cytoplasmic thiol cofactor, such as reduced glutathione (GSH). Additionally, the intracellular enzyme protein disulfide isomerase, or similar enzymes capable of cleaving disulfide bonds, may also contribute to the preferential cleavage of disulfide bonds inside cells. GSH is reported to be present in cells in the concentration range of 0.5-10 mM, compared with a significantly lower concentration of GSH or cysteine in plasma at approximately 5 µM. This is especially true for tumor cells, where irregular blood flow leads to a hypoxic state, resulting in enhanced activity of reductive enzymes and therefore in even higher glutathione concentrations.

N H

N H

S

S

OH requires activation

S

S

O

H2N N H

O O

S

S

NO2

PNP: no activation required

Fig: 17: Attachment of a disulfide-based linker to a primary amine functionalized payload.

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H N

O O

In addition, the stability of disulfide linkers can be finetuned by neighboring methylation. Methyl groups are bulky enough to have a significant influence on the thermodynamic stability of the disulfide bridge.

While one additional methyl group already enhances the stability drastically, two methyl groups make the disulfide bond practically stable towards reductive cleavage. A methylation number of three or four will completely lock the disulfide bridge towards further modifications.

NH2

H N

HO O

R1

R1

S

S

S

S

R2

GSH

O

O

N H SH

NH2 HO

+ Cys

R2

S

R1

disulfide isomerase

OH O

S

S

R2

S

R2

HS

O

R2

R1

S

S

R2

R1

S

S

R2

S

R1

S

R2

Fig. 18: Finetuning of payload release by variations of the disulfide-based linker.

References: → Self-immolative Linkers Literally Bridge Disulfide Chemistry and the Realm of Thiol-Free Drugs; C. F. Riber; A. A. A. Smith, A. N. Zelikin; Adv Healthcare Mater 2015; 4(12): 1887-1890. https://doi.org/10.1002/adhm.201500344 → Linker Technologies for Antibody-Drug Conjugates; B. Nolting; Antibody-Drug Conjugates L. Ducry 2013; 1045: 71-100. https://doi.org/10.1007/978-1-62703-541-5_5 → Disulfide-Based Self-Immolative Linkers and Functional Bioconjugates for Biological Applications; Z. Deng, J. Hu, S. Liu; Macromol Rapid Commun 2020; 41: e1900531. https://doi.org/10.1002/marc.201900531 → Reduction-Triggered Transformation of Disulfide-Containing Micelles at Chemically Tunable Rates; Z. Deng, S. Yuan, R. X. Xu, H. Liang, S. Liu; Angew. Chem. Int. Ed. 2018; 57: 8896-8900. https://doi.org/10.1002/anie.201802909

Another linker type for the conjugation to primary amines are pH-sensitive diisopropylsilyl linkers.

These linkers are intended to remain stable while circulating in plasma at neutral conditions (pH 7.3-7.5) and are cleaved under mildly acidic conditions, e.g. upon internalization into endosomal (pH 5.6-6.5) or lysosomal (pH 4.5-5.0) compartments.

O Si O

O

O O

NO2

H2N O Si O

O

HN O

Fig: 19: Attachment of a diisopropylsilyl-based linker to a primary amine functionalized payload.

References: → A versatile acid-labile linker for antibody drug conjugates; M. C. Finniss, K. S. Chu, C. J. Bowerman, J. C. Luft, Z. A. Haroon, J. M. DeSimone; Med. Chem. Commun. 2014; 5: 1355-1358. https://doi.org/10.1039/C4MD00150H → Novel Silyl Ether-Based Acid-Cleavable Antibody-MMAE Conjugates with Appropriate Stability and Efficacy; Y. Wang, S. Fan, D. Xiao, F. Xie, W. Li, W. Zhong, X. Zhou; Cancers 2019; 11(7): 957. https://doi.org/10.3390/cancers11070957

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Custom Synthesis → Acid-labile Linkers; E.A. Savoy, F.P. Olatunji. H. Yoon, N. Mesbahi, J.R. Knight, C.E. Berkman; in Chemical Linkers in Antibody-Drug Conjugates (ADCs); edited by Floris van Delft, John M. Lambert; Royal Society of Chemistry 2022; ISSN 2041-3203

Trimethyl-lock: The steric demand of three closely positioned methyl groups favors the cleavage of a carbonyl bond by lacton formation. The acidity of the phenol is sufficient to accelerate lactonization at neutral pH and any residue carrying a hydroxyl or amino function will be unlocked, i.e. tracelessly released.

O

H N

O

H N

OH

N H O PG

H2N

O PG

Activation

PG: o-nitrobenzyl, o-nitroveratryl, acetyl

.

Fig: 20: Attachment of a trimethyl-lock to a primary amine functionalized payload.

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For the conjugation to tertiary amines, the chemical composition of the linker needs to be adapted as follows:

Peptidic linkers, e.g. Val-Ala, Val-Cit + p-aminobenzyl chloride:

H N

O

R N H

R1 N R2

H N O

Cl

H N

O

R N H

H N

R2

O

R1 N+

Ala: R = CH3 Cit: R = (CH2)3-NH(CO)-NH2

Fig: 21: Attachment of a peptidic linker to a tertiary amine functionalized payload.

PH-sensitive linkers, e.g. diisopropylsilyl linker

O Si O

Cl

R1 N R2

R2 O Si O

R1

N+

Fig: 22: Attachment of a diisopropylsilyl-based linker to a tertiary amine functionalized payload.

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References: → Prodrug Strategies to Improve the Solubility of the HCV NS5A Inhibitor Pibrentasvir (ABT-530); J. T. Randolph, E. A. Voight, S. N. Greszler, B. E. Uno, J. N. Newton, K. M. Gleason, D. Stolarik, C. Van Handel, D. A. J. Bow, D. A. DeGoey; J. Med. Chem. 2020; 63(19): 11034-11044. https://doi.org/10.1021/acs.jmedchem.0c00956 → Mechanistic Studies of the Photoinduced Quinone Trimethyl Lock Decaging Process; C. J. Regan, D. P. Walton, O. S. Shafaat, D. A. Dougherty; J. Am. Chem. Soc. 2017; 139(13): 4729-4736. https://doi.org/10.1021/jacs.6b12007 → Trimethyl lock: A trigger for molecular release in chemistry, biology, and pharmacology; M. N. Levine, R. T. Raines; Chem. Sci. 2012; 3: 2412-2420. https://doi.org/c2sc20536j → Photo-triggered fluorescent labelling of recombinant proteins in live cells; D. Jung, K. Sato, K. Min, A. Shigenaga, J. Jung, A. Otaka, Y. Known; Chem. Commun. 2015; 51: 9670-3. https://doi.org/10.1039/c5cc01067e → Detection of DT-diaphorase Enzyme with a ParaCEST MRI Contrast Agent; I. Daryaei, K. M. Jones, M. D. Pagel; Chem. Eur. J. 2017; 23: 6514-6517. https://doi.org/10.1002/chem.201700721 → Syntheses and kinetic studies of cyclisation-based self-immolative spacers; S. Huvelle, A. Alouane, T. Le Saux, L. Jullien, F. Schmidt; Org. Biomol. Chem. 2017; 15: 3435-3443. https://doi.org/10.1039/c7ob00121e → Invention of stimulus-responsive peptide-bond-cleaving residue (Spr) and its application to chemical biology tools; A. Shigenaga, J. Yamamoto, T. Kohiki, T. Inokuma, A. Otaka; J. Pept. Sci. 2017; 23: 505-513. https://doi.org/10.1002/psc.2961 → Trimethyl Lock: A Multifunctional Molecular Tool for Drug Delivery, Cellular Imaging, and StimuliResponsive Materials; O. A. Okoh, P. Klahn; ChemBioChem 2018; 19: 1668-1694. https://doi.org/10.1002/cbic.201800269

2.2.3. Conjugation to Alcohols

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Besides amines, alcohols are another common motif in drugs, e.g. present in dexamethasone, α-amanitin, and doxorubicin.

OH

OH OH

HO

H

O

HO

N

H2N

O NH

HN O O

O

Dexamethasone

O

HN

H F

OH

H3C

O

O NH O

S

O

O

OH

O

NH N H

O

N H

OH H N

OMe O

OH

NH2

O O

O

α-Amanitin

OH

OH

OH

Doxorubicin

Fig. 23: Chemical structures of prominent drugs bearing an alcohol moiety.

The attachment of a linker to an alcohol-functionalized payload can be performed by “covering” the alcohol by an amine, e.g. by introducing N,N’-dimethylaminoethyl (DMAE). Thus, all strategies for amine payloads described above (peptidic linkers, disulfide-based linkers, pH-sensitive diisopropylsilyl linkers, trimethyl locks) can be applied accordingly.

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Custom Synthesis DMAE

S

O

S

N

O N

O

O

O

Clascoteron

O

H

O

O

O

O

H

O

S

HO

N

H

O H

H

N

H O

O

Fig. 24: Attachment of Clascoteron to a disulfide-based linker via DMAE and linker self-immolation.

References: → Natural Product Bis-Intercalator Depsipeptides as a New Class of Payloads for Antibody-Drug Conjugates; A. S. Ratnayake, L.-p. Chang, L. N. Tumey, F. Loganzo, J. A. Chemler, M. Wagenaar, S Musto, F. Li, J. E. Janso, T. E. Ballard, B. Rago, G. L. Steele, W. Ding, X. Feng, C. Hosselet, V. Buklan, J. Lucas, F. E. Koehn, C. J. O’Donnell, E. I. Graziani; Bioconjugate Chem. 2019; 30(1): 200-209. https://doi.org/10.1021/acs.bioconjchem.8b00843 → Drug-induced phospholipidosis confounds drug repurposing for SARS-CoV-2; T. A. Tummino, V. V. Rezelj, B. Fischer, A. Fischer, M. J. O’Meara, B. Monel, T. Vallet, K. M. White, Z. Zhang, A. Alon, H. Schadt, H. R. O’Donnell, J. Lyu, R. Rosales, B. L. McGovern, R. Rathnasinghe, S. Jangra, M. Schotsaert, J.-R. Galarneau, N. J. Krogan, L. Urban, K. M. Shokat, A. C. Kruse, A. García-Sastre, O. Schwartz, F. Moretti, M. Vignuzzi, F. Pognan, B. K. Shoichet; Science 2021; 373(6554): 541-547. https://doi.org/10.1126/science.abi4708

Figure 25 shows an example of a linked drug for ADC construction. Okilactomycin, a highly toxic payload (IC 50 = 2 nM) is attached to a tetrapeptide linker via para-aminobenzyl alcohol. The PAB group is tracelessly cleaved after hydrolysis of the amide bond. The Ala-Leu-Ala-Leu tetramer sequence acts as a

substrate to cathepsin B, which specifically hydrolysis the amide bond to para-aminobenzyl. Thus, this linker specifically degrades in the lysosome, only, and is stable in plasma.

Besides the linker itself and its attachment to the drug, solubility of the whole construct needs to be considered. In the example below, payload and linker are rather hydrophobic. To improve overall solubility and hydrophilicity, a poly(ethylene glycol) is added. Finally, the whole conjugate needs to be attached to a carrier. The shown compound is intended to be attached to nucleophiles, like amino functions of lysines of an antibody. Standard activation with NHS esters will result in low conjugation yields, as NHS ester hydrolysis will be the preferred reaction. Benzotriazole esters are stable at standard coupling conditions and will provide high yields.

O

H

O

N H

H

H N

O O

O O

H

N H

O H N

N H O

O

H N

O

N H

n

O

N N

O

O

Part 1: Okilactomycin, a highly toxic payload

Part 2: PAB-Leu-Ala-Leu-Ala

Part 3: PEG moiety

Fig. 25: Example for an enzyme-cleavable linker for antibody-drug conjugation.

25

N

O

Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

Part 4: Benzotriazole for further conjugation

O

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As the above example shows, there are many aspects to be considered during linker design and ADC construction.

Key questions are: • Do you require permanent or cleavable linkage? Under which conditions should the linker be cleaved and when does it need to be stable?

• Which functional moieties are present in the drug you want to conjugate?

• Which functional groups are present at the carrier side?

• How is the overall solubility of your drug in the desired environment?

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Knowing about your needs will help us finding the best solution for your application!

For more information on linker technologies and an overview of our available catalogue products, please see our brochure Linkerology ®.

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26

Custom Synthesis 2.3. Photoresponsive Derivatives Our main focus is on diazirines and photocleavable groups.

Our main focus is on diazirines and photocleavable groups. Light is an ideal external trigger for a variety of reasons. It can be modulated in its intensity (dosage control) and it can be focused to very small areas (sub-micron accuracy) with high temporal and spatial precision in a non-invasive fashion, depending on wavelength, intensity, and duration.

Thus, photoresponsive building blocks are attaining increasing attention for various applications ranging from peptide synthesis and controlled protein activation to tunable and dynamic materials.

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For more background information on photochemistry and a list of available catalogue products, please see our brochure Photochemistry.

2.3.1. Diazirine-modified Amino Acids Diazirines are widely used in photoaffinity labeling (PAL) to trap noncovalent interactions with biomolecules. Irradiation of diazirines with UV light (ca. 350 nm - 360 nm) yields a highly reactive carbene species that can undergo insertions into C-C, C-H, O-H and X-H (X = heteroatom) bonds of neighboring molecules to irreversibly form a covalent bond. The diazirine moiety is the smallest of all photophores, so introduction of a diazirine-bearing amino acid into a peptide or protein usually does not impair its biological activity. Further advantages of diazirine crosslinkers are their stability at room temperature, as well as their relative stability to nucleophiles, and to both acidic and basic conditions.

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N N

N

R

N

Sar-R-V-Y-V-H-P-F

Sar-R-V-Y-V-H-P-F

125

125

I

I

Internalization

R

R

Sar-R-V-Y-V-H-P-F UV irradiation

125

I

noncovalent binding

covalent bound

Live Cell

Live Cell

Fig. 26: Use of photo-phenylalanine for the identification of angiotensin-II receptor binding sites; 125I is used as a radiotracer.

References: → Labling Preferences of Diazirines with Protein Biomolecules; A. V. West, G. Muncipinto, H.-Y. Wu, A. C. Huang, M. T. Labenski, L. H. Jones, C. M. Woo; J. Am. Chem. Soc. 2021; 143(17): 6691-6700. https://doi.org/10.1021/jacs.1c02509 → Amino Acid Insertion Frequencies Arising from Photoproducts Generated Using Aliphatic Diazirines; D. S. Ziemianowicz, R. Bomgarden, C. Etienne, D. C. Shcriemer; J. Am. Soc. Mass Spectrom. 2017; 28: 2011-2021. https://doi.org/10.1007/s13361-017-1730-z → A bifunctional amino acid to study protein-protein interactions; T. Yang, X. Li, X. D. Li; RSC Adv. 2020; 10: 42076-42083. https://doi.org/10.1039/D0RA09110C → Stereospecific Synthesis of a Carbene-Generating Angiotensin II Analogue for Comparative Photoaffinity Labeling: Improved Incorporation and Absence of Methionine Selectivity; D. Fillion, M. Deraët, B. J. Holleran and E. Escher; J. Med. Chem. 2006; 49: 2200-2209. https://doi.org/10.1021/jm050958a → Covalent modifier-type aggregation inhibitor of amyloid-β based on a cyclo-KLVFF motif; R. Kino, T. Araya, T. Arai, Y. Sohma and M. Kanai; Bioorg & Med Chem Lett 2015; 25: 2972-2975. https://doi.org/10.1016/j.bmcl.2015.05.027 → Probing Protein-Protein Interactions with a Genetically Encoded Photocrosslinking Amino Acid; Hui-wang Ai, Weijun Shen, Amit Sagi, Peng R. Chen, and Peter G. Schultz; ChemBioChem 2011; 12: 1854–1857. https://doi.org/10.1002/cbic.201100194 → Aliphatic Diazirines as Photoaffinity Probes for Proteins: Recent Developments; J. Das; Chem Rev 2011; 111: 4405-4417. https://doi.org/10.1021/cr1002722

2.3.2.Photocleavable Linkers Typically, photocleavage proceeds under neutral conditions using UV light and can either be performed in batch or using flow chemistry. Furthermore, photolabile linkers are orthogonal to standard peptide chemistry reaction conditions, thus enabling the use of a wide variety of amino acid protecting groups.

Figure 27 shows exemplarily the photochemical cleavage that occurs in different nitrobenzyl (ONB) linker systems. The photochromic properties of NB-based linkers are readily tuned to respond to cytocompatible light doses and are widely utilized in cell culture and other biological applications.

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Custom Synthesis

(A)

O2N O

(B)

O

ON

OH

OCH3

+

hν Payload

O2N

O O

OCH3

O2N

OH H N

O

O

H N

+

hν Payload

O

Fig. 27: Mechanism for the photochemical cleavage that occurs in the (A) ortho-nitrobenzyl linker, (B) ortho-nitrophenylethyl linker.

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Interested? Get in contact to inquire about your customized photocleavable linker!

References:

→ Chapter 9 – Photocleavable linkers: design and applications in nanotechnology; S. K. Choi; MNT 2020; 243-275. https://doi.org/10.1016/B978-0-12-817840-9.00009-6 → Photolabile Linkers: Exploiting Labile Bond Chemistry to Control Mode and Rate of Hydrogel Degradation and Protein Release; P. J. LeValley, R. Neelarapu, B. P. Sutherland, S Dasgupta, C. J. Kloxin, A. M. Kloxin; J. Am. Chem. Soc. 2020; 142(10): 4671-4679. https://doi.org/10.1021/jacs.9b11564 → A traceless photocleavable linker for the automated glycan assembly of carbohydrates with free reducing ends; M. Wilsdorf, D. Schmidt, M. P. Bartetzko, P. Dallabernardina, F. Schuhmacher, P. H. Seeberger, F. Pfrengle; Chem. Commun. 2016; 52: 10187-10189. https://doi.org/10.1039/C6CC04954K → A photochemical approach for controlled drug release in targeted drug delivery; S. K. Choi, M. Verma, J. Silpe, R. E. Moody, K. Tang, J. J. Hanson, J. R. Baker Jr.; Bioorg. Med. Chem. 2012; 20: 1281-1290. https://doi.org/10.1016/j.bmc.2011.12.020 → Photolytic Mass Laddering for Fast Characterization of Oligomers on Single Resin Beads; K. Burgess, C. I. Martinez, D. H. Russell, H. Shin, A. J. Zhang; J. Org. Chem. 1997; 62(17): 5662-5663. https://doi.org/10.1021/jo970866w → Direct Monitoring of Organic Reactions on Polymeric Supports; M R Carrasco, M. C. Fitzgerald, Y. Oda, S. B. H. Kent; Tetrahedron Lett. 1997; 38(36): 6331-6334. https://doi.org/10.1016/S0040-4039(97)01456-1

2.3.3. Photo-Fatty-Acids Related to the topic Linkerology® our portfolio includes a range of fatty acid building blocks bearing a diazirine moiety. Thus, those derivatives may serve as bifunctional cross-linkers. The diazirine moiety can be placed at different positions of the aliphatic chain and various modified fatty acids are available allowing providing a versatile tool for structure-activity-relationship studies.

As an example, within our portfolio, we are offering the following derivatives. Of course, many more are available based on custom synthesis! Inquire for your derivative of choice!

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N

N

O

O

OH

OH

Photo-hexanoic acid RL-2900

O

N

N

Photo-palmitic acid RL-3740

OH N

N

Photo-stearic acid RL-3750

Fig. 28: Structure examples for photo-fatty acids.

References: → Preparation of Short Oligonucleotides via the Phosphoramidite Method Using a Tetrazole Promoter in a Catalytic Manner; Y. Hayakawa, M. Kataoka; J. Am. Chem. Soc. 1997; 119(49): 11758-11762. https://doi.org/10.1021/ja970685b → Cholesterol binds to synaptophysin and is required for biogenesis of synaptic vesicles; C. Thiele, M. J. Hannah, F. Fahrenholz, W. B. Huttner; Nat. Cell Biol. 2000; 2(1): 42-49. https://doi.org/10.1038/71366 → Global Mapping of Protein-Lipid Interactions by Using Modified Choline-Containing Phospholipids Metabolically Synthesized in Live Cells; D. Wang, S. Du, A. Cazenave-Gassiot, J. Ge, J.-S. Lee, M. R. Wenk, S. Q. Yao; Angew. Chem. Int. Ed. Engl. 2017; 56(21): 5829-5833. https://doi.org/10.1002/anie.201702509 → Cross-linking chemistry and biology: development of multifunctional photoaffinity probes; T. Tomohiro, M. Hashimoto, Y. Hatanaka; Chem. Record 2005; 5(6): 385-395. https://doi.org/10.1002/tcr.20058 → Recent Progress in Diazirine-Based Photoaffinity Labeling; M. Hashimoto, Y. Hatanaka; Eur. J. Org. Chem.

2008; 2008(15): 2513-2523. https://doi.org/10.1002/ejoc.200701069 → Fishing for Drug Targets: A Focus on Diazirine Photoaffinity Probe Synthesis; J. R. Hill, A. A. B. Robertson; J. Med. Chem. 2018; 61: 6945−6963. https://doi.org/10.1021/acs.jmedchem.7b01561

2.4. Polymers We cover the full range from PEGs over poly(amino acid)s, poly(sarcosine)s and poly(oxazoline)s to polyamines and various copolymers.

One of the main applications for polymers such as poly(ethylene glycol)s (PEGs) and poly(amino acid)s is for drug delivery. Novel delivery systems are constantly developed and sought after in order to alter the physicochemical and pharmacokinetic properties of drug molecules and to deliver them effectively in a controlled manner.

By tuning formulations and thus a drug’s “delivery properties”, ideal results for a drug and a certain application can be achieved and its full potential can be developed.

Attaching polymers which are tolerated by the physiologic systems, such as poly(amino acids), poly(ethylene glycol)s or other variants improves drastically their bioavailability and biodistribution and turns sensitive biomolecules into robust drugs. First attempts with polymers were made already in the 1960s – either by attaching the therapeutic agent covalently to a polymer or by entrapping it non-covalently in a polymer nanoparticle. Over the years, polymers have garnered attention in the evolution of drug delivery technologies for both water-soluble and hydrophobic drug molecules.

At Iris Biotech, we are offering various technologies to deliver pharmaceutical ingredients. Most frequently reported in literature are poly(ethylene glycol)s (PEGs) as well as poly(amino acid)s.

Besides our catalogue products, we are offering custom synthesis of your polymer of choice fitting best for your application.

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Custom Synthesis For your custom synthesis inquiry, please provide the following information: • polymer chain length or molecular weight • functionality on head • functionality on tail (pay attention whether it is compatible with the other terminus) • quantity (grams to kg) • quality (research grade or GMP) • dispersity (uniform or polydisperse) • if existent, functional group on side chain

2.4.1. Poly(ethylene glycol)s (PEGs) The first polymer-drug conjugates that showed promising results contained poly(ethyleneglycol) (PEG).

PEG is made of monomer units connected via an ether bond. The pharmacological effects of PEG and many other first generation polymer attachments are mainly of physical nature. They act solubilizing due to their hydrophilicity, prevent degradation, and reduce immunogenicity by shielding the pharmaceutical and prevent excretion by increasing its hydrodynamic radius.

Fig. 29: Pharmacokinetic properties of a PEGylated drug in comparison with a non-PEGylated drug.

PEGs show a spectrum of unique physical and chemical properties, which have been described in

literature extensively by the pioneers in PEGylation: Harris, Veronese and Hermanson. PEG derivatives are available from pure, uniform, discrete molecules with short chain lengths or even one ethylene oxide unit only, to long polydisperse constructs, both linear and branched.

For the (custom) synthesis of PEGs and other hydrophilic polymers specific know-how is required. The high solubility of such polymers in practically every solvent makes synthesis and particularly purification a challenging task. PEG starting material and PEG product normally display similar solubility.

Normal purification technologies like precipitation, crystallization, liquid/liquid extraction or even column chromatography hardly result in good purification results. The second challenge is the absence of good chromophores for UV absorption or fluorescence detection. Product specific analytical methods are required in order to provide accurate and reliable information about impurities, yield and quality in general at each production step.

We have chemical platforms available to attach any possible functional group on each of the two termini. Thus, a large variety of homo- and hetero-bifunctional polymers can be supplied.

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Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

Fig. 30: Overview of possible chemical modifications of PEGs. However, in particular the heavily crowded patent landscape for PEGs, their non-biodegradability and the observation of anti-PEG antibodies due to PEG accumulation led to the fact that plenty of new carriers have been developed.

References: → On the biodegradability of polyethylene glycol, polypeptoids and poly(2-oxazoline)s; J. Ulbricht, R. Jordan, R. Luxenhofer; Biomaterials 2014; 35: 4848-4861. https://doi.org/10.1016/j.biomaterials.2014.02.029 → Improvements in protein PEGylation: pegylated interferons for treatment of hepatitis C; A. Kozlowski, J. M. Harris; C. J. Control Release 2001; 72: 217-224. https://doi.org/10.1016/S0168-3659(01)00277-2 → Peptide and protein PEGylation: a review of problems and solutions; F. M. Veronese; Biomaterials 2001; 22(5): 405-417. https://doi.org/10.1016/s0142-9612(00)00193-9 → PEGylation, successful approach to drug delivery; F. M. Veronese, G. Pasut; Drug Discov. 2005; 10(21): 1451-1458. https://doi.org/10.1016/S1359-6446(05)03575-0 → Advances in PEGylation of important biotech molecules: delivery aspects; S. M. Ryan, G. Mantovani, X. Wang, D. M. Haddleton, D. J. Brayden; Expert Opin. Drug Deliv. 2008; 5(4): 371-383. https://doi.org/10.1517/17425247.5.4.371 → Protein PEGylation: An overview of chemistry and process considerations; V. B. Damodaran, C. J. Fee; Eur. Pharm. Rev. 2010; 15(1): 18-26.

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For more background information on PEGylation and a list of available catalogue products, please see our brochure PEGylation.

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Custom Synthesis 2.4.2. Poly(sarcosine)s (PSars, PSRs) Among potential alternatives for polymer carriers, polypeptoids in general and polysarcosine (PSR) in particular stand out in terms of safety, synthetic control and versatility. Polysarcosine – originating from the natural, non-toxic amino acid sarcosine (N-methylglycine) – is the simplest polypeptoid and serves as biocompatible and degradable polymer. A wide range of functional terminal groups can be realized.

As PSR is intrinsically heterobifunctional (-COOH, -NH2), the scope of hetero-bifunctional building block design is extensive and easy to realize.

In response to the increasing regulatory demand for drug delivery systems we are focused on high precision polymers. Iris Biotech offers monofunctional, homo- and heterobifunctional polysarcosines with a wide variety of functional groups. Degrees of polymerization (n) may range from below 10 to above 1,000.

Thus, molar masses of approx. 1 kg/mol to 100 kg/mol are feasible.

Fig. 31: We provide narrow molecular weight distribution and reproducible and scalable manufacturing.

References: → Suppressive immune response of poly-(sarcosine) chains in peptide-nanosheets in contrast to polymeric micelles; E. Hara, M. Ueda, C. J. Kim, A. Makino, I. Hara, E. Ozeki, S. Kimura; J. Pept. Sci. 2014; 20: 570-577. https://doi.org/10.1002/psc.2655 → On the biodegradability of polyethylene glycol, polypeptoids and poly(2-oxazoline)s; J. Ulbricht, R. Jordan, R. Luxenhofer; Biomaterials 2014; 35: 4848-4861. https://doi.org/10.1016/j.biomaterials.2014.02.029 → Polypeptoids: A Perfect Match for Molecular Definition and Macromolecular Engineering? R. Luxenhofer, C. Fetsch, A. Grossmann; J. Polym. Sci.: Part A: Polym. Chem. 2013; 51: 2731-2752. https://doi.org/10.1002/pola.26687 → Polysarcosine as an Alternative to PEG for Therapeutic Protein Conjugation; Y. Hu, Y. Hou, H. Wang, H. Lu; Bioconjugate Chem. 2018; 29(7): 2232-2238. https://doi.org/10.1021/acs.bioconjchem.8b00237 → Polysarcosine-containing copolymers: Synthesis, characterization, self-assembly, and applications; A. Birke, J. Ling, M. Barz; Prog. Polym. Sci. 2018; 81: 163-208. https://doi.org/10.1016/j.progpolymsci.2018.01.002 → Polysarcosine-Functionalized Lipid Nanoparticles for Therapeutic mRNA Delivery; S. S. Nogueira, A. Schlegel, K. Maxeiner, B. Weber, M. Barz, M. A. Schroer, C. E. Blanchet, D. I. Svergun, S. Ramishetti, D. Peer, P. Langguth, U. Sahin, H. Haas; ACS Appl. Nano Mater. 2020; 3(11): 10634-10645. https://doi.org/10.1021/acsanm.0c01834

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2.4.3. Poly(amino acid)s Eventhough PEGs still represent the most frequently used polymer for drug delivery, several possible side effects and complications are reported for this type of polymer, e.g. non-biodegradability/accumulation and immunogenicity. Besides, growing knowledge on drug delivery technologies allows to create “intelligent” systems which can help transporting a payload to a target destination or even to destinations where it could not go without the polymer’s help.

Biodegradable poly(amino acid)s appear very attractive in this context. However, their availability in sufficient quality and quantity for broad pharmaceutical application was a bottleneck in the first years. At Iris Biotech, we offer high-quality poly(amino acid)s (PArg, PGlu, PLys, POr) as well as copolymers thereof.

Those poly(amino acids) show the same pallet of diversity as PEGs and PSRs enriched by the capability to functionalize the side chain. The repeating functional group is an amide bond, just like in any natural peptide and protein. Thus, one of the major benefits of those polymers is that they are typically cleaved by enzymes into nontoxic substances and are thus biodegradable and biocompatible.

O

O F1

N Hn

F1

F2

HN Poly-Arginine

N Hn

O

NH N H

O

O

F2

F1

O N Hn

F2

F1

N Hn

R

NH HN

R Poly-Glutamic acid

F2

Poly-Lysine

R

R

Poly-Ornithine

Variation of: number of repeating units n, dispersity, copolymer or single polymer F1: alloc, amine, Boc, carbonyl, carboxyl, Cbz-amine, Fmoc, iodoacetyl, lipoic acid, maleimide, thiol, ...

F2: alcohol, aldehyde, alkyne, azide, biotin, cyclooctyne, tetrazine, trans-cyclooctene, norbornene, ...

R: alkyl, antibodies, benzyl, biomarkers, DNA, DOTA, dyes, enzymes, fatty acid, PEG, peptides, RNA, ...

Fig. 32: General chemical structures of poly(amino acid)s and possibilities for functionalization.

References: → Rational design of polyarginine nanocapsules intended to help peptides overcoming intestinal barriers; Z. Niu, E. Tedesco, F. Benetti, A. Mabondzo, I. M. Montagner, I. Marigo, D. Gonzalez-Touceda, S. Tovar, C. Diéguez, M. J. Santander-Ortega, M. J. Alonso; JCR 2017; 263: 4-17. https://doi.org/10.1016/j.jconrel.2017.02.024 → Polyarginine nanocapsules: a new platform for intracellular drug delivery; M. V. Lozano, G. Lollo, M. Alonso-Nocelo, J. Brea, A. Vidal, D. Torres, M. J. Alonso; J. Nanoparticle Res. 2013; 15: 1515. https://doi.org/10.1007/s11051-013-1515-7 → Suppressive immune response of poly-(sarcosine) chains in peptide-nanosheets in contrast to polymeric micelles; E. Hara, M. Ueda, C. J. Kim, A. Makino, I. Hara, E. Ozeki, S. Kimura; J. Pept. Sci. 2014; 20: 570-577. https://doi.org/10.1002/psc.2655

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Custom Synthesis → Thermoresponsive release from poly(Glu(OMe))-block-poly(Sar) microcapsules with surface-grafting of poly(N-isopropylacrylamide); T. Kidchob, S. Kimura, Y. Imanishi; J. Control. Release 1998; 50: 205-14. https://doi.org/10.1016/s0168-3659(97)00135-1 → Amphiphilic poly(Ala)-b-poly(Sar) microspheres loaded with hydrophobic drug; T. Kidchob, S. Kimura, Y. Imanishi; J. Control. Release 1998; 51: 241-248. https://doi.org/10.1016/s0168-3659(97)00176-4 → On the biodegradability of polyethylene glycol, polypeptoids and poly(2-oxazoline)s; J. Ulbricht, R. Jordan, R. Luxenhofer; Biomaterials 2014; 35: 4848-4861. https://doi.org/10.1016/j.biomaterials.2014.02.029 → Polyamide/Poly(Amino Acid) Polymers for Drug Delivery; S. H. S. Boddu, P. Bhagav, P. K. Karla, S. Jacob, M. D. Adatiya, T. M. Dhameliya, K. M. Ranch, A. K. Tiwari; J. Funct. Biomater. 2021; 12(4): 58. https://doi.org/10.3390/jfb12040058

2.4.4.Poly(2-oxazolines) (POXs) A quantum leap in polymer therapeutics came with the development of Poly(2-oxazolines) (POxs). POx is intrinsically heterobifunctional (-COOH, -NH2), therefore, the scope of the heterofunctional buil-

ding-block design is extensive and easy to realize. Additionally, they offer the possibility to vary the polymer property within a wide range. Through sophisticated choice of side chain residues polymer properties can be fine-tuned to display specific properties of hydrophilicity and hydrophobicity. The carrier molecule can specifically be equipped with properties like thermoresponsivity, low or high viscosity, glass transition temperature, stealth behavior.

The polymer backbone of POXs is not a polyamide as for poly(amino acid)s but a polyamine. Due to the missing amide bonds, the poly(2-oxazolines) are typically not biodegradable by human enzymes and thus these polymers have a much longer plasma half-life in vivo.

F1

N O

F2 n

R

Poly-(2-oxazolines) Variation of: number of repeating units n, dispersity, copolymer or single polymer F1: alloc, amine, Boc, carbonyl, carboxyl, Cbz-amine, Fmoc, iodoacetyl, lipoic acid, maleimide, thiol, ...

F2: alcohol, aldehyde, alkyne, azide, biotin, cyclooctyne, tetrazine, trans-cyclooctene, norbornene, ...

R: fluoroalkyl (hydrophobic and surface active), longer alkyl chains (insoluble in water), methyl (watersoluble), PEG (highly water soluble), side chains for surface interaction, side chains with reactive functional groups Fig. 33: Structure examples for poly(2-oxazolines) and examples for functionalization of the termini.

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References: → Amphiphilic polymers based on polyoxazoline as relevant nanovectors for photodynamic therapy; A. Oudin, J. Chauvin, L. Gibot, M.-P. Rols, S. Balor, D. Goudounèche, B. Payré, B. Lonetti, P. Vicendo, A.-F. Mingotaud, V. Lapinte; J. Mater. Chem. B 2019; 7: 4973-4982. https://doi.org/10.1039/C9TB00118B → Polyoxazoline biointerfaces by surface grafting; G. Morgese, E. M. Benetti; Eur. Polym. J. 2017; 88: 470-485. https://doi.org/10.1016/j.eurpolymj.2016.11.003 → Polyoxazoline: Chemistry, Properties, and Applications in Drug Delivery; T. X. Viegas, M. D. Bentley, J. M. Harris, Z Fang, K. Yoon, B. Dizman, R. Weimer, A. Mero, G. Pasut, F. M. Veronese; Bioconjugate Chem.

2011; 22(5): 976-986. https://doi.org/10.1021/bc200049d

2.4.5.Copolymers Another attractive feature of the polymers presented is the fact that they can be combined with each other to form different types of copolymers, e.g. grafted polymers, random copolymers or block copolymers. This allows us to modify parameters such as size, conformation, charge, solubility, geometry, and topology and opens a toolbox to an almost unlimited number of combinations specifically tailored to your particular needs.

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For more background information on Polymers for Drug Delivery and a list of available catalogue products, please see our brochure Polymer Therapeutics.

2.4.6.Formulation Services Finding the best formulation for a drug product can be a long and nerve-wracking process – especially if one has not used a certain delivery technology before. Therefore, better benefit from the years of know-how of our specialists. Our formulation team can identify the best delivery technology for your payload. Once the best delivery system is found, we can also perform all further formulation screening and optimization for your drug project. Finally, we can provide GMP fill & finish of aseptic vials and other non-aseptic formats.

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Custom Synthesis 2.4.7. Spermines, Spermidines and other Polyamines Polyamines such as ethylene diamine and its higher homologues are important feedstocks for the chemical industry. Compounds like putrescine, spermidine, and spermine play important roles in both eukaryotic and prokaryotic cells and show many other different biological functions. As cations they bind to DNA, and, in structure, they represent compounds with multiple positive charges with welldefined spaced intervals.

We have technology available to custom manufacture any type of polyamine with the following parameters: • polyamines with a varying number of nitrogens • spacers with different numbers of carbons • bearing additional linkers, residues or protecting groups at any nitrogen

PG1 H2N

x

N

PG1 H2N

x

N

O N

y

PG2

N

OH

N H O

y

NH2

PG2

Fig. 34: General chemical structures of polyamines available at Iris Biotech.

References: → Translational recoding as a feedback controller: systems approaches reveal polyamine-specific effects on the antizyme ribosomal frameshift; C. Rato, S. R. Amirova, D. G. Bates, I. Stansfield, H. M. Wallace; Nucleic Acids Res. 2011; 39(11): 4587-4597. https://doi.org/10.1093/nar/gkq1349 → The Critical Roles of Polyamines in Regulating ColE7 Production and Restricting ColE7 Uptake of the Colicin-producing Escherichia coli*; Y.H. Pan, C.-C. Liao, C.-C. Kuo, K.-J. Duan, P.-H. Liang, H. S. Yuan, S.-T. Hu, K.-F. Chak; J. Biol. Chem. 2006; 281(19): 13083-13091. https://doi.org/10.1074/jbc.M511365200 → Synthesis and applications of polyamine amino acid residues: improving the bioactivity of an analgesic neuropeptide, neurotensin; L. Zhang, H.-K. Lee, T. H. Pruess, H. Steve White, G. Bulaj; J. Med. Chem. 2009; 52(6): 1514-1517. https://doi.org/10.1021/jm801481y → Role of polyamines and ethylene as modulators of plant senescence; S. Pandey, S. A. Ranade, P. K. Nagar, N. Kumar; J. Biosci. 2000; 25: 291-299. https://doi.org/10.1007/BF02703938

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For more background information on spermines, spermidines and polyamines and a list of available catalogue products, please see our brochure Diamines & Polyamines.

2.5. Development Projects At Iris Biotech, we will find the best way for the realization of your project.

It can happen that the route of synthesis, yield and purity for a specific molecule is uncertain to predict precisely. However, we have ideas, how to reach the target and need to carry out several trial experiments and research, followed by developing the trials to a robust process, in order to find a suitable route of production.

Typical tasks are: • lab-scale de novo route development as basis for a later competitive, sustainable manufacturing • optimization or re-designing of an existing synthetic route, in order to increase the efficiency of your processes with a selection of efficient technologies • finding a patent-free approach to your molecule

More complex questions such as whole project developments can be worked out on contract R&D basis.

This encompasses developments, which can typically be described as: finding the right molecule or polymer for a specific application e.g. in bioconjugation, analytics or material science.

This work typically leads to the development of a sustainable and scalable route of synthesis and can include production of your compound from lab scale to bulk. Payment is based on fee-for-service on full time equivalents (FTE) and for milestones.

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Custom Synthesis 2.6. Contract Manufacturing of Lab Samples according to your own Process Do you have an urgent need of your own compound in g or kg scale, but currently no lab space or manpower available?

We will implement your process in a professional environment. As a matter of course, everything concerning your process will be treated as strictly confidential. Following completion of the project, you will receive a comprehensive documentation from our skilled team of scientists, so you can easily follow and reproduce every step.

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Custom Synthesis

Code of Conduct As business activity of Iris Biotech GmbH impacts people’s lives and health, it must be operated in ethical and correct manner and act with integrity and responsibility. To ensure high ethical standards and fair business practices, Iris Biotech GmbH applies an integrated policy known as its Code of Conduct.

In 2001 Iris Biotech GmbH was founded just at the beginning of the Biotech movement and the first remarkable breakthrough of biotech pharma products. Although the biotech field is rather young compared to other industries we believe on long-term business, a good partnership between our business partners and Iris Biotech GmbH and a good reputation. It is our duty as well as our responsibility to maintain and to extend this over the next generations – based on the principles of an honourable and prudent tradesman which based upon the concept of honourable entrepreneurship.

This Code of Conduct has been developed following the “Voluntary Guidelines for Manufacturers of Fine Chemical Intermediates and Active Ingredients” issued by AIME (Agrochemical & Intermediates Manufacturers in Europe) and the requirements of some of our business associates.

Iris Biotech GmbH commits to hold this Code of Conduct and to include and apply its principles in the management system and the company policies.

Ethics Iris Biotech GmbH undertakes business in an ethical manner and acts with integrity. All corruption, extortion and embezzlement are prohibited. We do not pay or accept bribes or participate in other illegal inducements in business or government relationships. We conduct our business in compliance with all applicable anti-trust laws. Employees are encouraged to report concerns or illegal activities in the workplace, without threat of reprisal, intimidation or harassment.

Labour Iris Biotech GmbH is committed to uphold the human rights of workers and to treat them with dignity and respect. Child labour, workplace harassment, discrimination, and harsh and inhumane treatment are prohibited. Iris Biotech GmbH respects the rights of the employees to associate freely, join or not join labour unions, seek representation and join workers’ councils. Employees are paid and their working timetable is established according to applicable wage and labour laws. Employees are able to communicate openly with management regarding working conditions without threat of reprisal, intimidation or harassment.

General Policies Contracts and Secrecy Agreements are binding and the confidential information received is only used for intended purposes. Clear management and organizational structures exist to provide efficient normal working and to address problems quickly. Know-how is protected and intellectual property isrespected.

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Health and Safety Iris Biotech GmbH provides a safe and healthy working environment to the employees and protects them from overexposure to chemical and physical hazards. Products are produced, stored and shipped under the guidelines of the relevant chemical and safety legislation. Risks and emergency scenarios are identified and evaluated, and their possible impact is minimized by implementing emergency plans and written procedures. Safety information regarding hazardous materials is available to educate, train and protect workers from hazards. Preventive equipment and facilities maintenance is performed at suitable periods to reduce potential hazards. Employees are regularly trained in health and safety matters and are informed about product properties and risk classification when it is required.

Environment Iris Biotech GmbH operates in an environmentally responsible and efficient manner, minimizing adverse impacts on the environment. Waste streams are managed to ensure a safe handling, movement, storage, recycling and reuse, before and after being generated. Systems to prevent and mitigate accidental spills and releases to the environment are in place. All required environmental permits and licenses are obtained and their operational and reporting requirements are complied with.

Production and Quality Management A quality management system following the Good Distribution Practices (GDP rules) of Active Pharmaceutical Ingredients is established covering all the aspects of the worldwide distribution of products.

Regular audits are performed to evaluate the efficiency and fulfilling of the quality system. Process controls to provide reproducible product quality are established. There are preventive maintenance procedures to ensure plant reliability and the lowest risk of failure. Staff is trained periodically about GMP and GDP rules. Procedures are established and installations are designed to avoid cross contamination.

Batch and analytical records are kept for inspection and audit purposes for suitable periods according guidelines.

Research and Development Research and development staff education is appropriate to their functional activity and they are trained to develop, optimize and scale-up the processes. Intellectual property is respected and knowhow protected. Development of manufacturing processes reflects the principles of the Green Chemistry according to the American Chemical Society Green Chemistry Institute. Animal testing is not used unless alternatives are not scientifically valid or accepted by regulators. If animal testing is carried out, animals are treated so that pain and stress are minimized.

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Custom Synthesis

Terms and Conditions of Sales All orders placed by a buyer are accepted and all contracts are made subject to the terms which shall prevail and be effective notwithstanding any variations or additions contained in any order or other document submitted by the buyer. No modification of these terms shall be binding upon Iris Biotech GmbH unless made in writing by an authorised representative of Iris Biotech GmbH.

Placing of Orders Every order made by the buyer shall be deemed an offer by the buyer to purchase products from Iris Biotech GmbH and will not be binding on Iris Biotech GmbH until a duly authorised representative of Iris Biotech GmbH has accepted the offer made by the buyer. Iris Biotech GmbH may accept orders from commercial, educational or government organisations, but not from private individuals and Iris Biotech GmbH reserves the right to insist on a written order and/or references from the buyer before proceeding.

There is no minimum order value. At the time of acceptance of an order Iris Biotech GmbH will either arrange prompt despatch from stock or the manufacture/acquisition of material to satisfy the order. In the event of the latter Iris Biotech GmbH will indicate an estimated delivery date. In addition to all its other rights Iris Biotech GmbH reserves the right to refuse the subsequent cancellation of the order if Iris Biotech GmbH expects to deliver theproduct on or prior to the estimated delivery date. Time shall not be of the essence in respect of delivery of the products. If Iris Biotech GmbH is unable to deliver any products by reason of any circumstances beyond its reasonable control („Force Majeure“) then the period for delivery shall be extended by the time lost due to such Force Majeure. Details of Force Majeure will be forwarded by Iris Biotech GmbH to the buyer as soon as reasonably practicable.

Prices, Quotations and Payments Prices are subject to change. For the avoidance of doubt, the price advised by Iris Biotech GmbH at the time of the buyer placing the order shall supersede any previous price indications. The buyer must contact the local office of Iris Biotech GmbH before ordering if further information is required. Unless otherwise agreed by the buyer and Iris Biotech GmbH, the price shall be for delivery ex-works. In the event that the buyer requires delivery of the products otherwise than ex-works the buyer should contact the local office of Iris Biotech GmbH in order to detail its requirements. Iris Biotech GmbH shall, at its discretion, arrange the buyer‘s delivery requirements including, without limitation, transit insurance, the mode of transit (Iris Biotech GmbH reserves the right to vary the mode of transit if any regulations or other relevant considerations so require) and any special packaging requirements (including cylinders).

For the avoidance of doubt all costs of delivery and packaging in accordance with the buyer‘s requests over and above that of delivery in standard packaging ex-works shall be for the buyer‘s account unless otherwise agreed by both parties. Incoterms 2020 shall apply. Any tax, duty or charge imposed by governmental authority or otherwise and any other applicable taxes, duties or charges shall be for the buyer‘s account. Iris Biotech GmbH may, on request and where possible, provide quotations for multiple packs or bulk quantities, and non-listed items. Irrespective of the type of request or means of response all quotations must be accepted by the buyer without condition and in writing before an order will be accepted by Iris Biotech GmbH. Unless agreed in writing on different terms, quotations are valid for 30 days from the date thereof. Payment terms are net 30 days from invoice date unless otherwise agreed in writing. Iris Biotech GmbH reserves the right to request advance payment at its discretion. For overseas transactions the buyer shall pay all the banking charges of Iris Biotech GmbH. The buyer shall not be entitled to withhold or set-off payment for the products for any reason whatsoever. Government/

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Corporate Visa and MasterCard (and other such credit cards) may be accepted on approved accounts for payment of the products. Personal credit cards are not acceptable. Failure to comply with the terms of payment of Iris Biotech GmbH shall constitute default without reminder. In these circumstances Iris Biotech GmbH may (without prejudice to any other of its rights under these terms) charge interest to accrue on a daily basis at the rate of 2% per month from the date upon which payment falls due to the actual date of payment (such interest shall be paid monthly). If the buyer shall fail to fulfil the payment terms in respect of any invoice of Iris Biotech GmbH Iris Biotech GmbH may demand payment of all outstanding balances from the buyer whether due or not and/or cancel all outstanding orders and/or decline to make further deliveries or provision of services except upon receipt of cash or satisfactory securities.

Until payment by the buyer in full of the price and any other monies due to Iris Biotech GmbH in respect of all other products or services supplied or agreed to be supplied by Iris Biotech GmbH to the buyer (including but without limitation any costs of delivery) the property in the products shall remain vested in Iris Biotech GmbH.

Shipping, Packaging and Returns The buyer shall inspect goods immediately on receipt and inform Iris Biotech GmbH of any shortage or damage within five days. Quality problems must be notified within ten days of receipt. Goods must not be returned without prior written authorisation of Iris Biotech GmbH. Iris Biotech GmbH shall at its sole discretion replace the defective products (or parts thereof) free of charge or refund the price (or proportionate price) to buyer. Opened or damaged containers cannot be returned by the buyer without the written prior agreement of Iris Biotech GmbH. In the case of agreed damaged containers which cannot be so returned, the buyer assumes responsibility for the safe disposal of such containers in accordance with all applicable laws.

Product Quality, Specifications and Technical Information Products are analysed in the Quality Control laboratories of Iris Biotech GmbH’s production partners by methods and procedures which Iris Biotech GmbH considers appropriate. In the event of any dispute concerning reported discrepancies arising from the buyer’s analytical results, determined by the buyer’s own analytical procedures, Iris Biotech GmbH reserves the right to rely on the results of own analytical methods of Iris Biotech GmbH. Certificates of Analysis or Certificates of Conformity are available at the discretion of Iris Biotech GmbH for bulk orders but not normally for prepack orders. Iris Biotech GmbH reserves the right to make a charge for such certification. Specifications may change and reasonable variation from any value listed should not form the basis of a dispute. Any supply by Iris Biotech GmbH of bespoke or custom product for a buyer shall be to a specification agreed by both parties in writing.

Technical information, provided orally, in writing, or by electronic means by or on behalf of Iris Biotech GmbH, including any descriptions, references, illustrations or diagrams in any catalogue or brochure, is provided for guidance purposes only and is subject to change.

Safety All chemicals should be handled only by competent, suitably trained persons, familiar with laboratory procedures and potential chemical hazards. The burden of safe use of the products of Iris Biotech GmbH vests in the buyer. The buyer assumes all responsibility for warning his employees, and any persons who might reasonably be expected to come into contact with the products, of all risks to person and property in any way connected with the products and for instructing them in their safe handling and use.

The buyer also assumes the responsibility for the safe disposal of all products in accordance with all applicable laws.

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Custom Synthesis Uses, Warranties and Liabilities All products of Iris Biotech GmbH are intended for laboratory research purposes and unless otherwise stated on product labels, in the catalogue and product information sheet of Iris Biotech GmbH or in other literature furnished to the buyer, are not to be used for any other purposes, including but not limited to use as or as components in drugs for human or animal use, medical devices, cosmetics, food additives, household chemicals, agricultural or horticultural products or pesticides. Iris Biotech GmbH offers no warranty regarding the fitness of any product for a particular purpose and shall not be responsible for any loss or damage whatsoever arising there from. No warranty or representation is given by Iris Biotech GmbH that the products do not infringe any letters patent, trademarks, registered designs or other industrial rights. The buyer further warrants to Iris Biotech GmbH that any use of the products in the United States of America shall not result in the products becoming adulterated or misbranded within the meaning of the Federal Food, Drug and Cosmetic Act (or such equivalent legislation in force in the buyer‘s jurisdiction) and shall not be materials which may not, under sections 404, 505 or 512 of the Act, be introduced into interstate commerce. The buyer acknowledges that, since the products of Iris Biotech GmbH are intended for research purposes, they may not be on the Toxic Substances Control Act 1976 („TSCA“) inventory. The buyer warrants that it shall ensure that the products are approved for use under the TSCA (or such other equivalent legislation in force in the buyer‘s jurisdiction), if applicable. The buyer shall be responsible for complying with any legislation or regulations governing the use of the products and their importation into the country of destination (for the avoidance of doubt to include, without limitation, the TSCA and all its amendments, all EINECS, ELINCS and NONS regulations). If any licence or consent of any government or other authority shall be required for the acquisition, carriage or use of the products by the buyer the buyer shall obtain the same at its own expense and if necessary produce evidence of the same to Iris Biotech GmbH on demand. Failure to do so shall not entitle the buyer to withhold or delay payment. Any additional expenses or charges incurred by Iris Biotech GmbH resulting from such failure shall be for the buyer‘s account. Save for death or personal injury caused by negligence of Iris Biotech GmbH, sole obligation of Iris Biotech GmbH and buyer‘s exclusive remedy with respect to the products proved to the satisfaction of Iris Biotech GmbH to be defective or products incorrectly supplied shall be to accept the return of said products to Iris Biotech GmbH for refund of the actual purchase price paid by the buyer (or proportionate part thereof), or replacement of the defective product (or part thereof) with alternative product. Iris Biotech GmbH shall have no liability to the buyer under or arising directly or indirectly out of or otherwise in connection with the supply of products by Iris Biotech GmbH to the buyer and/or their re-sale or use by the buyer or for any product, process or services of the buyer which in any way comprises the product in contract tort (including negligence or breach of statutory duty) or otherwise for pure economic loss, loss of profit, business, reputation, depletion of brand, contracts, revenues or anticipated savings or for any special indirect or consequential damage or loss of any nature except as may otherwise be expressly provided for in these terms. All implied warranties, terms and representations in respect of the products (whether implied by statute or otherwise) are excluded to the fullest extent permitted by law. The buyer shall indemnify Iris Biotech GmbH for and against any and all losses, damages and expenses, including legal fees and other costs of defending any action, that Iris Biotech GmbH may sustain or incur as a result of any act or omission by the buyer, its officers, agents or employees, its successors or assignees, its customers or all other third parties, whether direct or indirect, in connection with the use of any product. For the avoidance of doubt and in the event that Iris Biotech GmbH supplies bespoke or custom product to the buyer‘s design or specification, this indemnity shall extend to include any claim by a third party that the manufacture of the product for the buyer or the use of the product by the buyer infringes the intellectual property rights of any third party.

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Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

General Iris Biotech GmbH shall be entitled to assign or sub-contract all or any of its rights and obligations hereunder. The buyer shall not be entitled to assign, transfer, sub-contract or otherwise delegate any of its rights or obligations hereunder. Any delay or forbearance by Iris Biotech GmbH in exercising any right or remedy under these terms shall not constitute a waiver of such right or remedy. If any provision of these terms is held by any competent authority to be invalid or unenforceable in whole or in part the validity of the other provisions of these terms and the remainder of the provision in question shall not be affected. These terms shall be governed by German Law and the German Courts shall have exclusive jurisdiction for the hearing of any dispute between the parties save in relation to enforcement where the jurisdiction of the German Courts shall be non-exclusive.

Notes

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Get in Contact Iris Biotech GmbH Adalbert-Zoellner-Str. 1 95615 Marktredwitz Germany

+49 (0) 9231 97121-0 +49 (0) 9231 97121-99 info@iris-biotech.de www.iris-biotech.de

Distribution Partners The list contains the current distributors of Iris Biotech in different regions of the world. The latest list of distribution partners and contact details is available at: www.iris-biotech.de/distribution-partner

China: Chengdu Yoo Technology Co., Ltd.

Japan: BizCom Japan, Inc. Shigematsu & Co., Ltd Cosmo Bio Co., Ltd.

USA & Canada: Peptide Solutions LLC

India, Bangladesh, Oman, Sri Lanka, United Arab Emirates: Sumit Biosciences Pvt Ltd.

Singapore, Thailand, Malaysia, Indonesia, Vietnam, Philippines, Brunei, Burma (Myanmar), Laos, Cambodia, Timor-Leste: SciClix Pte. Ltd.

Iris Biotech GmbH • Email: info@iris-biotech.de • www.iris-biotech.de • Empowering Peptide Innovation

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Empowering Peptide Innovation