80 BACTERIAL FERMENTATIONS 



larly since fatty acid oxidation and synthesis in various 

 organisms had been shown to be related in this way. Con- 

 sequently we investigated the origin of the fermentation 

 products by use of purines specifically labeled with C 14 . 



1 NH— CO— ^C0 2 



C0 2 -< — 2 CO | 5 C— 7 NH' 



I j || T" /CO— ^HCOOH 



3 NH-t 4 Cj- 9 NH 



CH 2 — NH 2 



I 

 COOH 



Fig. 5. Uric Acid Breakdown by Clostridia. 



The results, summarized qualitatively in Fig. 5, show that 

 the degradation of purines by Clostridia bears a close resem- 

 blance to the general pattern of purine biosynthesis. Thus, 

 carbon atoms 1 and 2 and the nitrogen atom of glycine are 

 converted to purine carbon atoms 4, 5, and 7 respectively 

 in the pigeon, and are formed from these same purine 

 atoms in the fermentation. Carbon atoms 6 and 8 of purine 

 arise from carbon dioxide and formate, respectively, in the 

 biosynthesis and yield the same compounds in the fermen- 

 tation. The only significant difference between the two 

 processes is in the origin and fate of carbon atom 2 of 

 purine; in biosynthesis this carbon atom is derived from 

 formate, whereas in the fermentation it is converted to 

 carbon dioxide. This difference is attributable to the fact 

 that the primary synthetic product in the pigeon is hypo- 

 xanthine ribotide, which contains a reduced carbon atom 

 in the 2 position, whereas the purine that actually under- 

 goes cleavage in the fermentation is probably xanthine, 

 which contains an oxidized carbon atom in this position. 

 Experiments on the fermentation of unlabeled purines in 

 the presence of C 14 -labeled glycine, formate, or carbon 



