94 THE SYNTHESIS OF PROTEINS 



products, and that the amino acids and acid amides are formed 

 from the polypeptides. 



In Cicer arietinwn, there is a marked increase in the 

 amount of amino acids and their amides during germi- 

 nation, which increase is at the expense of the proteins.* 

 Similarly there is an accumulation of amides in the shoots of 

 germinating peas ; the amount of amide nitrogen in the seed 

 leaves fluctuates much at first but in the later stages of ger- 

 mination there is a marked increase, whilst, concurrently, 

 the a-amino acids decrease in amount and finally disappear. 

 From these relationships between the amides and amino acids, 

 Sure and Tottingham f consider that amino acids serve for the 

 production of amides. 



Of the cleavage products of proteins, asparagine is amongst 

 the more conspicuous in the plant. It occurs in the de- 

 veloping parts | in greater abundance than in the members 

 where the reserve proteins are stored ; Schulze § found that 

 only 7-62 per cent, of asparagine occurred in the cotyledons, 

 whilst 31*81 per cent, occurred in the axis of the lupin. Also 

 the relative amounts of asparagine and aspartic acid show 

 considerable variation during germination and, in the last 

 stages, the amount of asparagine formed is in a proportion 

 greater than the amount of protein decomposed. 



Asparagine is possibly a secondary product. || According 

 to Prianischnikow,^[ in the germination in darkness of legu- 

 minous seeds, its origin is due to the oxidation of the amino 

 acids derived from the protein reserves, ammonia being formed 

 and then elaborated into asparagine. When etiolated seed- 

 lings are illuminated the asparagine disappears, being used in 

 the construction of new protein. 



The above facts relate to reproductive organs ; on the 



* Zlataroff : " Biochem. Zeitsch.," 1916, 75, 200. 



t Sure and Tottingham : " Journ. Biol. Chem.," iqtG, 26, 535. 



% This may easily be shown by germinating a lupin seed in the dark 

 until the hypocotyl is a few inches in length. On mounting a section of 

 the hypocotyl in strong alcohol and examining under the microscope, a 

 large number of crystals of asparagine will be seen. 



§ Schulze : " Landw. Jahrb.," 1878, 411. 



|| See Choate : " Bot. Gaz.," 1921. 71, 409. 



\ Prianischnikow : " Biochem. Zeit.," 1924, 150, 406. 



