Biochemical and molecular studies of human methenyltetrahydrofolate synthetase.

Biochemical and molecular analysis of glutamine synthetase gene in brassica napus L.

5,10-methenyltetrahydrofolate cyclohydrolase, rat liver and chemically catalysed formation of 5-formyltetrahydrofolate.

The 5,10-methenyltetrahydrofolate (5,10-CH=H4folate) synthetase catalyses the physiologically irreversible formation of 5,10-CH=H4folate from 5-formyltetrahydrofolate (5-HCO-H4folate) and ATP. It is not clear how (or if) 5-HCO-H4folate is formed in vivo. Using a spectrophotometric assay for 5-HCO-H4folate, human recombinant 5,10-CH=H4folate cyclohydrolase, which catalyses the hydrolysis of 5,10...

Methenyltetrahydrofolate synthetase prevents the inhibition of phosphoribosyl 5-aminoimidazole 4-carboxamide ribonucleotide formyltransferase by 5-formyltetrahydrofolate polyglutamates.

Methenyltetrahydrofolate synthetase (EC 6.3.3.2) catalyzes the irreversible ATP and Mg2+-dependent transformation of 5-formyltetrahydrofolate (N5-HCO-H4-pteroylglutamic acid (PteGlu] to 5,10-methenyltetrahydrofolate. The physiological function of this reaction remains unknown even though it is potentially involved in the intracellular metabolism of the large doses of N5-HCO-H4-PteGlu (leucovori...

Purification and properties of 5,10-methenyltetrahydrofolate cyclohydrolase from Clostridium formicoaceticum.

Methenyltetrahydrofolate cyclohydrolase (EC 3.5.4.9) from Clostridium formicoaceticum has been purified to a specific activity of 469 mumol min-1 mg-1 at 35 degrees C, pH 7.2. The purified enzyme is homogeneous as judged by polyacrylamide disc gel electrophoresis, sedimentation velocity, and gel filtration profiles. The molecular weight is 41,000 +/- 200 as determined by sedimentation equilibri...

Methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase-formyltetrahydrofolate synthetase: a multifunctional protein from porcine liver.

Methylenetetrahydrofolate dehydrogenase, methenyltetrahydrofolate cyclohydrolase, and formyltetrahydrofolate synthetase from porcine liver have been co-purified more than 500-fold to apparent homogeneity. The inability of three sequential chromatographic procedures followed by affinity chromatography using NADP+- or ATP-substituted Sepharose to resolve the three activities demonstrates that the...