title: Identification of amino acid residues essential for enzyme activity of sheep liver 5,10-methylenetetrahydrofolate reductase.
abstract: Sheep liver 5,10-methylenetetrahydrofolate reductase was subjected to specific chemical modification with phenylglyoxal, diethyl pyrocarbonate and N-bromosuccinimide. The second-order rate constants for inactivation were calculated to be 54 M-1 X min-1, 103 M-1 X min-1 and 154 M-1 X min-1 respectively. This inactivation could be prevented by incubation with substrates or products, suggesting that the residues modified, namely arginine, histidine and tryptophan, are essential for enzyme activity.
mesh_terms: D045103:5,10-Methylenetetrahydrofolate Reductase (FADH2); D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D001665:Binding Sites; D004047:Diethyl Pyrocarbonate / Q000494:pharmacology; D007700:Kinetics; D008024:Ligands; D008099:Liver / Q000201:enzymology*; D010088:Oxidoreductases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010658:Phenylglyoxal / Q000494:pharmacology; D012756:Sheep; D014364:Tryptophan / Q000032:analysis
chemical_list: D000596:Amino Acids; D008024:Ligands; D014364:Tryptophan; D010088:Oxidoreductases; D045103:5,10-Methylenetetrahydrofolate Reductase (FADH2); D004047:Diethyl Pyrocarbonate; D010658:Phenylglyoxal