ASPARAGINE 97 



acids are reconstructed into proteins ; that carbohydrate 

 is essential to the process, and corroborate the conclusion 

 arrived at on an earlier page, that light as such is of no direct 

 consequence ; and that asparagine plays a prominent part. 



As has been seen, asparagine may be produced from amino 

 acids, possibly by the combination of ammonia and aspartic 

 acid * to form ammonium aspartate which gives origin to the 

 asparagine by the loss of a molecule of water. Prianischnikov,f 

 whilst recognizing in ammonia the end product of protein 

 dissociation, considers that it also is an initial stage in the 

 formation of proteins, and, according to him, asparagine is 

 the form in which it is stored. 



Asparagine lends itself to condensation more or less readily, 

 and by simply boiling a solution, the dipeptide of aspartic 

 acid is formed.^ 



There is no definite information of the details of amino 

 acid synthesis in the plant. In the laboratory the following 

 synthesis have been effected (see Vol. I., p. 450) :— 



Ammonia + glyoxylic acid -> formylglycine and acetyl alanine 

 Ammonia + /J-vinyl acrylic acid ->- diamino valeric acid. 

 Ammonia + fumaric acid-> aspartic acid. 



If like synthesis occur in the plant, ammonia and unsaturated 

 acids are requisite. 



Nothing is known of the combination of amino acids into 

 the final protein ; it will, however, be remembered that 

 Fischer synthesized a number of polypeptides, some of 

 considerable complexity, from amino acids in the laboratory 

 (see Vol. I., p. 447). 



To summarize our little knowledge of the synthesis of 

 protein in the plant : nitrate is reduced to nitrite and possibly 

 to ammonia, which reacts with sugar, or a degradation pro- 

 duct of sugar, possibly an unsaturated acid, to form simple 

 amino acids which may give rise to asparagine, or other 

 amines, a temporary phase which can easily be decomposed 



* Schulze: loc. cit. Prianischnikov : " Ber. deut. bot. Gesells.," 1904, 

 22, 35. Treboux : id., 570. 



| Prianischnikov : " Bull. Agric. Intell.," 1017, 8, 204. 



t Ravenna and Bosinelli : " Rend. R. Acad. Lincei.," 1919, 28, ii, 113. 



vol. n. — 7 



