Deuterium Effects on Binding of Reduced Coenzyme Alcohol Dehydrogenase Isoenzyme EE
Karen Bush 1,
H. R. Mahler 1, and
V. J. Shiner Jr. 1
1 Department of Chemistry, Indiana University, Bloomington 47401
Determination of dissociation constants by two different methods yield the following mean values in 20 millimolar phosphate, pH 7.0, 25°C: 0.27 micromolar for reduced nicotinamide adenine dinucleotide (NADH); 0.29 micromolar for NADH with deuterium in the nicotinamide 4-B position (B-NADD); and 0.46 micromolar for NADH with deuterium in the nicotinamide 4-A position (A-NADD). These results indicate that dehydrogenases are capable of recognizing and distinguishing the appropriate hydrogen in the coenzyme already in the initial binding reaction.