282 



VI. ACETIC, FORMIC, AND PROPIONIC ACIDS 



.' CH2OH ; 



'CH2.NH2 . CHNH2 



^t-' I 



COOH COOH 



CH2OH CH2OH COOH 



I I + I + 



CH2NH2 > CH2N(CH3)3 > CHsNCCHj), 



^ '.CHalS-CH.CH.CHCOOH 

 I 

 XH, 



(CHa) 

 N— CH2COOH 



HC=C— CH2CHCOOH C=NH 



I I 



NHj NH2 



The Various Reactions in Which the Formj'l Radicle Has Been Shown to Participate^^i 



(5) Reactions in Which Formate Plays a Role 



a. Purine Synthesis (Reactions 1 and 2). Sonne and co-workers'^^ and 

 Karlsson and Barker '^^ reported that formic acid contributes to the 

 ureide carbons 2 and 8 of the uric acid synthesized and excreted by pigeons. 

 This same reaction also occurs in the rat,'^^ an animal which synthesizes 

 much less purine than does the bird. In the case of the fowl, it has been 

 recognized that practically all excreted nitrogen is converted into uric 

 acid before elimination. Skipper et aL'^^ reported that an antagonist- 

 induced folic acid deficiency in mice diminishes the incorporation of C'*- 

 formate into the nucleic acid purines. This inhibition appears to be specific 

 for formic acid, as the incorporation of C''*02 into purines is only partially 

 blocked, and tissue CO2 fixation is not affected. 



Greenberg'^^'^^® likewise demonstrated that, in the synthesis of hypox- 

 anthine, inosine-5-phosphate is one of the first purine derivatives to be 

 detected. Thus, it was found that, in the presence of a dialyzed extract 

 of pigeon liver, glycine, CO2, glutamine, CF, biotin, and ribose-1-phosphate 



1" J. L. Karlsson and H. A. Barker, J. Biol. Chem., 177, 597-599 (1949). 

 16' M. R. Heinrich and D. W. Wilson, /. Biol. Chem., 186, 447-460 (1950). 

 i«* H. E. Skipper, J. H. Mitchell, Jr., and L. L. Bennett, Jr., Cancer Research, 10, 510- 

 512 (1950). 



i«5 G. R. Greenberg, /. Biol. Chem., 190, 611-631 (1951). 

 i«6 G. R. Greenberg, Federation Proc, 10, 192 (1951). 



