Multiple inhibition of yeast alcohol dehydrogenase

Abstract

Multiple inhibition of the yeast alcohol dehydrogenase-catalyzed oxidation of ethanol was investigated; four different inhibitors were used that were known to function competitively with respect to NAD + in these reactions. The inhibitors, adenosine diphosphate ribose, adenosine diphosphate, N 1-methylnicotinamide chloride, and 1,10-phenanthroline, were studied in pairs to determine the extent to which interactions between inhibitors occur on the enzyme. The inhibitor pairs showing a maximum interaction or mutual exclusion were adenosine diphosphate riboseadenosine diphosphate, N 1-methylnicotinamide chloride-1,10-phenanthroline, adenosine diphosphate ribose-1,10-phenanthroline, adenosine diphosphate-1,10-phenanthroline, and N 1-methylnicotinamide chloride-adenosine diphosphate. A slight interaction was observed when the pair, adenosine diphosphate ribose- N 1-methylnicotinamide chloride was studied. Multiple inhibition studies with 1,10-phenanthroline were consistent with the binding of this inhibitor through interactions with the pyridinium site and the hydrophobic region of the enzyme.