338 PROTEINS 



and Kunlin * have been able to synthesize the acetyl and 

 formyl derivatives respectively of alanine and glycine by the 

 action of ammonia on glyoxylic acid, both of which sub- 

 stances are known to occur in plants. The changes involved 

 may be represented by the following formulae : — 



CHO CH2NHCHO 



2 I + NHj = I + HoO + CO2 



COOH COOH 



Glyoxylic acid Formylglycine 



CH2NHCHO CHjNH, 



I + H2O -> I + HCOOH 



COOH COOH 



Glycine 



Furthermore, Fischer f has been able to synthesize a di- 

 amino acid by the action of ammonia on sorbic acid, an un- 

 saturated acid occurring in the unripe berries of the mountain 

 ash ; also another unsaturated acid belonging to the same 

 series as sorbic acid, namely, /3-vinyl acrylic acid, has by the 

 action of ammonia been converted into diamino valeric acid, J 

 and further, aspartic acid § has been obtained by the action of 

 ammonia on fumaric acid. 



From the plant physiological point of view, however, the 

 interest of these latter discoveries is dependent on the occur- 

 rence in the plant both of unsaturated acids and of ammonia. 



The researches of Ehrlich 1| upon the action of yeast on 

 amino acids have led to some very interesting results ; it was 

 found that the addition of leucine or isoleucine to a ferment- 

 ing sugar solution gave rise to a production of inactive or 

 active amyl alcohol respectively, according to the following 

 schemes. 



CH,\ 



^CHCHoCH.OH + CO, + NH3 



Amyl alcohol 



)CHCHNH„COOH + H^O = " ^CHCH,OH + CO, + NH3 

 C2H5/ " C.Hs/ 



Isoleucine Active amyl alcohol 



The amounts of these alcohols produced are proportional 



*Erlenmeyer and Kunlin: " Ber. deut. chem. Gesells.," 1902, 35, 2438. 

 f Fischer and Schlotterbeck : id., 1904, 37, 2357. 

 J Fischer and Raske : id., 1905, 38, 3607. 



§Engel: " Compt. rend.," 1887, 104, 1805, and 1S85, 106, 1677. 

 II Ehrlich : " Ueber die Bedeutung des Eiweissstoffwechsels, etc. " " Samm- 

 lung chem. u. chem. tech. Vortrage," Stuttgart, 1911. 



