RATES OF BINDING OF REDUCED NICOTINAMIDE-ADENINE DINUCLEOTIDE ANALOGS TO LIVER ALCOHOL DEHYDROGENASE

The kinetics of the binding of reduced nicotinamide-adenine dinucleotide, reduced deamino nicotinamide-adenine dinucleotide, and reduced 3-acetylpyridine-adenine dinucleotide to liver alcohol dehydrogenase have been studied. The “on” and “off” velocities of the two analogs were compared with the values for reduced nicotinamide-adenine dinucleotide. The “on” velocity for reduced deamino nicotinamideadenine dinucleotide was much slower while its “off” velocity was the same as for reduced nicotinamide adenine dinucleotide. The “on” velocity of reduced 3-acetylpyridine-adenine dinucleotide was the same as for reduced nicotinamide-adenine dinucleotide but its “off” velocity was much faster. This indicates that the adenine ring is not bound subsequent to the nicotinamide ring and that the amide group binding is independent of the spectral shift due to pyridine ring binding. The possible sequential nature of the binding reaction and its mechanistic implications are discussed. © 1969, American Chemical Society. All rights reserved.