Enzymic oxidation of formic acid.

Interest in the metabolic fate of formic acid has been renewed as the result of recent experiments showing active incorporation of carbon-labeled formate into normal body constituents of the pigeon (l-3) and the rat (4, 5). Prior to these findings, enzymes capable of catalyzing the oxidation of formic acid had been reported, widely distributed in plant and animal tissues (6). Only in the case of a preparation from green peas was the reaction well defined, however. Adler and Sreenivasaya (7) demonstrated that direct reduction of diphosphopyridine nucleotide (DPN) by formate was catalyzed by dialyzed pea extracts. This finding extended the work of Andersson (8) who had shown that DPN was necessary for the reduction of methylene blue by formate in such preparations. The object of the present study was to obtain additional information about enzyme systems capable of oxidizing formic acid. Studies on the enzyme from green peas were therefore extended. Attempts to demonstrate the presence in animal tissues of soluble enzymes capable of oxidizing formate were also made and were successful in the case of rat liver and kidney.