Formic Acid Activation in Plants. I. Purification, Properties and Distribution of Formyltetrahydrofolate Synthetase.

Tetrahydrofolic acid derivatives have been found to be the active cofactors in a number of reactions which involve 1-carbon moieties (9). The participation of tetrahydrofolate enzyme systems in purine and histidine biosynthesis has been well established (9). N10-formyltetrahydrofolate apparently functions in purine synthesis by serving as a 1-carbon donor (2, 9). The synthesis of N10-fornlyltetrahydrofolate is carried out by the enzyme formyltetrahydrofolate synthetase which catalyzes the following reaction: Formate + ATP + tetrahydrofolate N'0-formyltetrahydrofolate + ADP + Pi The enzyme was first demonstrated by Greenberg et al. (4) in pigeon liver homogenates. It has been purified from acetone powders of pigeon liver (5), from human erythrocytes (1), from Micrococcus aerogenes (12), and from Clostridium cylindrosporurn (10). The enzyme has been isolated in crystalline form from the latter organism. Existence of the enzyme in tissues of higher plants has not been reported. This paper describes the purification and properties of the enzyme from tissues of higher plants. Studies of the activation of formyltetrahydrofolate synthetase by potassium and magnesium are reported in the following paper (6).