Cellular oxidations and the synthesis of amino-acids and amides in plants 



5 - 



- oL 



>- 



z 



^3 



So.G 



"Total N 



Insoluble N 



J0LU8LE' N 



Glutamine 



Glutamic Acid 

 © 



ALANINE 



Hours 



Figure 3. Changes in nitrogenous constituents during the assimilation of 

 ammonia —N by yeast. Total nitrogen, insoluble (protein) and soluble fractions 

 are shown in the upper part of the figure, and the chief amino-acids and amides 



in the lower part. 



It is clear that 15 N supplied as ammonia is quickly incorporated into glutamine; 

 the abundance in the amide approaches that of the ammonia-N in the tissues after 

 10I hours, thus providing direct evidence of a primary synthesis. Asparagine amide, 

 on the other hand, has a lower abundance which gradually rises during assimilation ; 

 it is possible that this amide is formed secondarily from glutamine. The protein-N 



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