Intermediary metabolism of Clostridium acidi-urici. I. Formation of pyruvate from glycine.

Fermentation of purines by Clostridium acidiuirici was observed in early studies (Barker and Beck, 1941) to yield acetate, carbon dioxide, ammonia, glycine and formate. The formation of glycine and formate was confirmed more recently by Radin and Barker (1953), and Bradshaw and Beck (1953). Sagers and Beck (1956) have demonstrated, as was first suggested by Radin and Barker (1953), that L-serine is converted quantitatively to pyruvate and ammonia bv intact cells or cell-free extracts of C. acidiurici. Results of tracer studies (Sagers and Beck, 1956) suggested that glycine and formate unite to yield L-serine which is then converted via pyruvate to acetate, carbon dioxide and ammonia, the sole end-products of normal growth and cell suspension activity. Attempts to produce L-serine (or pyruvate) from glycine and formate using cells or extracts of C. acidi-urici were unsuccessful until cognizance was taken of the work of Blakley (1954) and Kisliuk and Sakami (1955). These investigators demonstrated that formaldehyde and not formate is the active C, compound in the formation of serine from glycine in a tetrahydrofolic acid-dependent reaction carried out by partially purified ("dowex-1"-chloride treated) pigeon liver extracts. The purpose of this paper is to show that pyruvic acid is formed (most probably via L-serine) from formaldehyde and glycine by cell-free preparations of C. acidi-urici and that of several folic acid-like compounds studied, 5,6,7, 8-tetrahydrofolic acid (THFA)3 is the 1 Support by the National Cancer Institute (C1475) is gratefully acknowledged. 2 At present, National Science Foundation preDoctoral Fellow, Department of Bacteriology, University of Illinois, Urbana, Illinois. 3 The following abbreviations are used in the manuscript: THFA = 5,6,7,8-tetrahydrofolic acid; FA = folic acid, pteroylglutamic acid; CF = citrovorum factor, leucovorin, N -formyl-THFA; DPN = diphosphopyridine nucleotide; DPNH = reduced diphosphopyridine nucleotide; FIG = formiminoglycine. most effective in restoring this activity to dowex-1-chloride treated extracts.