[Purification and properties of the tetrahydropteroylglutamate methyltransferase from green beans (Phaseolus vulgaris) (author's transl)].
The tetrahydropteroylglutamate methyltransferase from green beans (Phaseolus vulgaris) has been purified 80-fold by ion exchange chromatography and gel filtration. Optimal methyl transfer is found at pH 6.5 and 39 degrees C. Even at 0 degrees C, however, a considerable catalytic rate is observed. The Michaelis-Menten constants for homocysteine and 5-methyltetrahydropteroylglutamate are 0.43mM and 2.4 mM, respectively. Magnesium ions enhance the activity. Even purified preparations appear to contain traces of magnesium ions firmly bound, since a residual activity is found without addition of magnesium salts. Though the reaction requires anaerobiosis, an excess of reducing agents is inhibitory. The molecular weight of the transferase, determined by gel filtration, is 40 000 +/- 6%.
D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase / Q000302:isolation & purification / Q000378:metabolism; D001205:Ascorbic Acid / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008780:Methyltransferases / Q000302:isolation & purification; D008970:Molecular Weight; D010944:Plants / Q000201:enzymology*; D013696:Temperature
D008780:Methyltransferases; D013766:5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase; D001205:Ascorbic Acid; D004229:Dithiothreitol
Reinigung und Eigenschaften der Tetrahydropteroylglutamat-Methyltransferase aus Bohnen (Phaseolus vulgaris).