Citrovorum Factor Cyclodehydrase¹

Mechanism for the Coupling of ATP Hydrolysis to the Conversion of 5-Formyltetrahydrofolate to 5,10-Methenyltetrahydrofolate

“…The enzyme activity was first found in sheep liver acetone powder extracts by Peters and Greenberg (1) and later studied by Kay et al and Greenberg et al (2,3). This enzyme has been purified to homogeneity from both prokaryotic and eukaryotic sources (4 -6).…”

Folic Acid Coenzymes and One‐Carbon Metabolism

“…reaction (26)). Upon fractionation of the sheep liver isomerase, Peters and Greenberg (333) have been able to purify an enzyme, Citrovorum Factor cyclodehydrase, which utilizes f6FH4 and ATP to produce a substance similar to, but not identical with, f5-lo-FH4. This compound was isolated by chromatography on Dowex 1-Cl, and found to differ from f5-10FH4 in ultraviolet absorption spectrum ( A, , , a t 343 mp instead of 356 mp).…”

Further Studies on N5-Formyltetrahydrofolic Acid Cyclodehydrase*

“…Optimum pH of Cyclodehydrase Reaction. Previous studies on a cruder enzyme preparation indicated that the optimum pH for the reaction was at 3.8 (Peters and Greenberg, 1958). This has been repeated using a preparation which assayed 9.2 units/mg.…”

“…Enzyme Inhibitors. It was shown by Peters and Greenberg (1958) that the 7Vs-formyl-FH4 cyclodehydrase was inhibited by the sulfhydryl agents, p-mercuribenzoate and o-iodosobenzoate. The inhibition could be prevented by the presence of reduced glutathione.…”