342 " PROTEINS 



alcohol, in which prolamins are insoluble, and ether. The 

 ether is added in order to make the precipitation more com- 

 plete and also to hold any fats which may have been ex- 

 tracted by the alcohol. 



SYNTHESIS OF AMINO ACIDS IN THE PLANT. 



With regard to the synthesis of animo acids within the 

 plant, it is of interest to note that in the laboratory Erlenmeyer 

 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 CH 2 NHCHO 



2 | + NH 3 = + H 2 O + CO 2 



COOH COOH 



Glyoxylic acid Formylglycine 



CH 2 NHCHO CHaNH,, 



| + H 2 O -> 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,| 

 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 



* 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 1885, 106, 1677. 

 || Ehrlich : " Ueber die Bedeutung des Eiweisstoffwechsels, etc.," " Samm- 

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



