Role of the essential thiol groups of yeast alcohol dehydrogenase

Abstract

1. Yeast alcohol dehydrogenase inactivated by reaction with iodoacetamide retains 85% of the original NADH-binding capacity as measured under conditions of saturating coenzyme concentration. 2. The dissociation constant of the enzyme–NADH complex is unaffected by inactivation of the enzyme with iodoacetamide, and the affinity of the enzyme for NAD+ and pyridine-3-aldehyde–adenine dinucleotide (PAAD+) appears to be similarly unaffected. 3. Enzyme inactivated with iodoacetamide has lost the ability to form normal ternary complexes of the type enzyme–NADH–acetamide and enzyme–PAAD+–hydroxylamine that are characteristic of the native enzyme.