The relationship of folic acid to formate metabolism in the rat; formate incorporation into purines.

The considerations which prompted an investigation of the r61e of folic acid in formate metabolism were discussed in an earlier paper (1) in which it was reported that rats deficient in this vitamin incorporated less of a standard dose of CY4-formate into certain amino acids and heme than did rats fed folic acid. There is abundant microbiological evidence to indicate an interrelationship between folic acid and the purines (2-5). The accumulation of 4-aminoimidazole-5-carboxamide in cultures of Escherichiu coli inhibited with sulfanilamide (6) suggests very strongly that folic acid controls the incorporation of formate at least into carbon atom 2 of the purines. In addition, Skipper et ab. (7) have demonstrated that the incorporation of labeled formate into the total nucleoprotein of mice is decreased by the administration of folic acid antagonists. This study was undertaken to demonstrate whether folic acid affects the incorporation and relative location of labeled formate in nucleic acid purines in the rat.