title: Methylenetetrahydrofolate dehydrogenase, methenyltetrahydrofolate cyclohydrolase and formyltetrahydrofolate synthetase from porcine liver. Isolation of a dehydrogenase-cyclohydrolase fragment from the multifunctional enzyme.
abstract: Tryptic digestion of a multifunctional enzyme from porcine liver containing methylenetetrahydrofolate dehydrogenase (5,10-methylenetetrahydrofolate: NADP+ oxidoreductase, EC 1.5.1.5), methenyltetrahydrofolate cyclohydrolase (5,10-methenyltetrahydrofolate 5-hydrolase, EC 3.5.4.9) and formyltetrahydrofolate synthetase (formate:tetrahydrofolate ligase, EC 6.3.4.3) activities destroys the synthetase. A fragment containing both dehydrogenase and cyclohydrolase activities has been isolated by affinity chromatography on an NADP+-Sepharose affinity column. The purified fragment is homogeneous on dodecyl sulfate-polyacrylamide gel electrophoresis where its molecular weight was determined as 33 000 +/- 1200 compared with 100 000 for the undigested protein. The cyclohydrolase activity retains sensitivity to inhibition by NADP+, MgATP and ATP.
mesh_terms: D000619:Aminohydrolases / Q000302:isolation & purification*; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D005574:Formate-Tetrahydrofolate Ligase / Q000302:isolation & purification*; D008025:Ligases / Q000302:isolation & purification*; D008099:Liver / Q000201:enzymology*; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP) / Q000302:isolation & purification*; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000302:isolation & purification*; D010088:Oxidoreductases / Q000302:isolation & purification*; D013552:Swine; D013763:Tetrahydrofolates; D014357:Trypsin
chemical_list: D009097:Multienzyme Complexes; D013763:Tetrahydrofolates; D010088:Oxidoreductases; D008754:Methylenetetrahydrofolate Dehydrogenase (NADP); D014357:Trypsin; D000619:Aminohydrolases; D008025:Ligases; D005574:Formate-Tetrahydrofolate Ligase