Dimethyl sulfoxide: an inhibitor of liver alcohol dehydrogenase.

Dimethyl sulfoxide inhibits horse liver alcohol dehydrogenase. In the direction of aldehyde reduction, this inhibition is competitive with aldehyde, with an inhibition constant of 5 x 10(-3)M. Dimethyl sulfoxide reacts with the binary complex consisting of enzyme and the reduced form of nicotinamide -adenine dinucleotide to form a highly fluorescent ternary complex, with a dissociation constant similar to the inhibition constant. The inhibition of aldehyde reduction can be interpreted as due to competition between aldehyde and dimethyl sulfoxide for the carbonyl binding site of the above-mentioned binary complex.