Evidence for catalytic site cysteine and histidine by chemical modification of beta-hydroxy-beta-methylglutaryl-coenzyme A reductase.
S-(4-Bromo-2,3-dioxobutyl)-coenzyme A inactivates both yeast and rat liver beta-hydroxy-beta-methylglutaryl-coenzyme A reductase. The inactivation is irreversible, complete in 15 s, and proportional to the concentration of the reagent. beta-Hydroxy-beta-methylglutaryl-CoA provides protection against inactivation, whereas NADPH does not. Inactivation is attributed to reaction with an essential cysteine at the beta-hydroxy-beta-methylglutaryl-CoA binding site. Experiments with other active site-directed reagents confirm the involvement of a cysteine and support the presence of an active-site histidine, but rule out the participation of arginine or serine.
D000214:Acyl Coenzyme A / Q000378:metabolism; D000345:Affinity Labels / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D003545:Cysteine / Q000378:metabolism; D006639:Histidine / Q000378:metabolism; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism*; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D008099:Liver / Q000201:enzymology; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D013696:Temperature
D000214:Acyl Coenzyme A; D000345:Affinity Labels; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D013439:Sulfhydryl Reagents; D006639:Histidine; D006903:Hydroxymethylglutaryl CoA Reductases; D003545:Cysteine