328 PROTEINS 



and Kunlin * have been able to synthesize the acetyl and 

 formyl deriv^atives 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 + NH3 = I + H.,o + CO2 



COOH COOH 



Glyoxylic acid Formylglycine 



CH2NHCHO CHgNH,, 



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, y8-vinyl acrylic acid, has by the 

 action of ammonia been converted into diamine valeric acid, 4 

 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 || 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. 



CH3X CH,\ 



)CHCHoCHNH„COOH + H.^ = >CHCHoCHoOH + CO., + NH3 



CH3/ " ■ CH3/ 



Leucine Amyl alcohol 



CH3 \ CH3 \ 



)CHCHNH2C00H + H,0 = )CHCH„OH + CO., + NH3 



C^Hg/ " C2H5/ 



Isoleucine Active amyl alcohol 



The amounts of these alcohols produced are proportional 



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

 t Fischer and Schlotterbeck ; id., 1904, 37, 2357. 

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



§Engel: " Compt. rend.," 1887, 104, 1805, and 1885, 106, 1677. 

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

 lung chem. u. chem. tech. Vortrage," Stuttgart, 19 ir. 



