The role of sulphydryl groups of yeast carboxylase

Abstract
The effect of thiol reagents was studied on purified yeast carboxylase prepared by Green''s method. Heavy metals are the fastest reacting inhibitors; alkylating agents slowest. Heavy metals and arsenicals form stable, slightly dissociated mercaptides; Pyruvates interfere with the inhibition, cocarboxylase does not. Cysteine, glutathione and 2,3 dimercaptopropanol protect carboxylase against sulfhydryl reagents and reactivate considerably the poisoned enzyme. Relative effectiveness of cysteine and 2,3 dimercaptopropanol varies with the sulfhydryl reagent.