(.Reprinted from Nature,
Vol. li3, p.
1141,
Jutte 12. 1954\
Photosynthesis of Amino-Acids from Paraformaldehyde and potassium Nitrate Tsn role of light in the synthesis of amino_acids .prolerns rn pJalts is still noL very clearl. lnd rrev_lousty rt was believed rhat, in higher plants, synthesi,q of proteins is confined'to the"leaves2 and might depend on light. It, has bu"., k.ro"* tfr*t, protems are formed in leaves when there is an adequate supply of carbohyd.rates, and. there-is some evidence that tho rate of protein'synthesis in leaves is greater in the light rhan in the darkr, - the parenb substance from which higher plants derive _their nitrogen is njbrate. ff,i.'-rrli""tu i" reduced to niurite in l,he roots and stem of plants. Schimperr has found that nitrites u,"" u,i**v" present in the Jiving leaf in the dark and they alJupi,""" l" the light, I have now been able to s;nrthesize amino-acids from paraformaldehyd.e ancl pltassiurn rrlt""ls *ltf, the help of light. Three grqup: of l,hreo sol utions each were prepared.
Uroup ^ I solutions contained 2 grn. of paraiormalde_ hyde, and I c,c. of 6 N ferric cf,lorid"e'each.--f:o tfre
three solutions were added I gm., 0.5 grrr. O.-ZS g. of potassium nitrate respective\2. Tfie solutions ""a were kept in 250 c.c. Sigcol biakor. u,.rd t00 c.c. oi Jlstiifed water was added in each. All i,hree were exposed" to
bright sunlight for 80 hr. The temperature-.juriutio., during the exposure was between iS" and ZS.l. C. of fhree solutions *as kept-in the , A similar group dark. _The third group. which was simitar to the others but contained no ferric chioride, wa,s kept in
sunlight,
exposure of 80 hr. the solutions were -an the tested for presence of amino_acids by Giri,s crrcular paper chromatography methods,i using butanol - acetic acicl - wat-er - ad solvent, and nin_ Aft-or
hydrin as the developing reagent for producing e- -- ^"r-'" " Many of these amino-acids were qualitatively separated and their identification confirmed by coiours with amino-acitl.
paper chromatography as described. by Giri, 9lr9$ar Krishnamurthy and othersf. The solutions kept in the dark did not show the presence of amino-acid. Those containing no ferric chlor'.de but.kept in the light showed the-formar,ion 01 a lew amino-acids, but the rings were verv faint
and no dofinite conclusion could be d"aw'rrl
.f.he
Solutions containing ferric chioride and kept in the iight showed the formaLion o.[ deflnile rings. Arnong the solutions containing ferric chloride kept
in lhe light, that containing I gm, ofl potassium nitrate gave rings identified as duo to asparagine, serine, arginine bnd proline. Ilowever; two rings,
one pale yellow of rolative -Br 0'34 and another deip yellow of relative -Rr 0'39, are also seen, which could not be identified. The solut'ion which contained 0..5 gm..of potassiu-rn nitrate shov/ed the presence of asparagine, arginine, serine, proline and ornithine. The solution which contained only 0.25 grn. of pot,assium nitra,te shqwed the presence of valine, histidine, proline, lysine, serino, aspariie acid, glycine, asparagine and arginine. There also appeared a light yellow ring of relative Rt 4"57 and a dark yellow ring of relativd Rt 0.43, neither of which could be
identified.
A1l the three solutions containing ferric chlorido and kept in the light became st'rongiy acidic on exposnre and thoir pH varied between 1 to 0.8.
Tho solutions containing no ferric chloride and kept in the light had pH betweerl 4'5 to 4'8 at the end. The solutions kept in tho dark had pH about'6. An attempt to separate these amino-acids from the mixture containing 0.25 grn; of potassiurn nitrate was mado by circular papor chromatography, and crystalline serino, aspartic acid, glycine-and asparagine wore separated ; only a few crystals of each were obtained. Altempts to separa,te histidine, arginine, lysino q4d proline ha,ve met with littld success so far. Quantitativo separation of theso amino-acids will be undertakon shorbly. . Preliminary analyses of only three of the separa,ted amino'acids have boen done so far.-
. Serine, On boiling with
sulphriric acid it gave, pyruvic acids : oHcHr-c}I(NEr)COOH * CHr--C(NHr)-COOH -*
a,mmonia' and
CH3-C(:-NII)-COOH + CH, CO.COOH + NIIg., The amino-acid gave glyceric acid and a small quanbiby of acetaldehyde on treatment wibh nitrous
acid. It was oxidized to periodic acidro.
glycolaldehydee with
Aspartic aci,cl,. It, formed a barium salt which was insoluble in alcohol. The acid did not pdss orqer into pyrrolidone carboxylic acid. in hot aqueous solution. This distinguishes it from glutamic acidrl. .Tho acid yields nitrogon on treating wilh nitrous acid.
Tho amino-acid gave a benzoyl Eterivative of 1629 e . and hydantoic acid, 'melting point l6t" C. melting pgint
Asparag'ine. . On boiling the crystals of'asparagine with hydrochloric acid, or,-aspartic acid waS obtained.
\-\-l
On boiting with dilute alkali, it, yielded ammonia and
: :: ' .r'r,at,'I?5e,C,:,; it produegd o(-naphthvlhvjtantoic:acid, ',, :-', : . = mpl-fing.point'_lg9dC.
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l i: ....:.".]....]l'ChernistrYDepart'ment,.'.J. . :.. .I rr '. - ..;, Alleha.bad Univeisity,. '
u{,Ilahabad. . . I Stiles, .w,,.S., '.:Photosynthesis", Z0B (tongma-ns, Green: antl,-eo., London,
s
1925).
Pfeffer, W;, "The Physiology of ptants", 1 (Oxford, 1900).
'. : .1 "Phqtosynthesist:, 220 (Chemical Catalog Co;, New.-York. 1926). , sehinp.ei; ,8oi..2.., 45, 65 (L888): , . .t , : ,i, ,. 'o G-!rir:K;, V..):aQuirent.,9ci.,:20, zb8 (1951), ..,.r.:' . ;,- ,, .,,, - -.'Gti, 6.:!,, and prasail, A. L;,. N_, .Nature, 16g; ?86 (19t1): . '.r,i 'Gr4, K. V! _Krishn?mulhy, K., ancl Venkitmubramirnian, T. A., -,
Aunent Sci.,2t, 11 (t952)-
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Z. lthgsi,ol. Chem.,_L5}, t77 (Lgzil:, ,- . 'gNicolet and Shinn, J. Amer, Chsm. Soc.,6l, 1615 (1929).. n'tilch and Schieider, J. Biot. Ch.em., fAt, fa (fgAt). ,t; ' 11 X'oremaa, Binihem. J., 8, 461, 481 (1914). ., '' '" f'_Setizieqhe,
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