INTERMEDIARY METABOLISM AND GROWTH 



Alanine and 

 other amino acids 



IPRA 

 FGAM 

 Guonylic 

 Glucosamine-6-P 

 Histidine-N-1 



(PRPP 

 FGAR 

 Xanthosinic 

 Fructose- 6 -P 

 Histidine precursor 



ATP, C02 ^Carl.amyl pnosphote 



Fig. 40. NH3 utilization and nitrogen transfer reactions. 



Levenberg et al., 1956). Mention should also be made of the fact that aspartic 

 acid is a precursor of [3-alanine and of pyrimidines. The former involves the 

 decarboxylation of aspartate. The first step in the latter process is the reaction of 

 aspartate with carbamyl phosphate to give ureidosuccinic acid (Lowenstein and 

 Cohen, 1956). Fig. 40 summarizes the NH3 fixation and nitrogen transfer reac- 

 tions discussed in this section. 



D. Porphyrin Synthesis 



As a result of tracer experiments it was inferred that the 34 carbon atoms and the 

 four nitrogen atoms of protoporphyrin of duck erythrocyte (Fig. 41) are derived 

 from labelled acetate and labelled glycine (Shemin and Wittenberg, 1951) in the 

 following manner: 



HC(5 



COOH 



Fig. 41. Protoporphyrin IX. 



