Affinity electrophoresis of human alcohol dehydrogenase (ADH) isozymes.

1. The effects of coenzyme NAD and related compounds on the electrophoretic properties of the human ADH isozymes have been examined by the technique of affinity electrophoresis. 2. Incorporation of NAD, NADH or AMP into a starch-gel matrix leads to retardation in the cathodal mobilities of the gamma 2 gamma 2 and alpha alpha isozymes, but not the beta 1 beta 1 and gamma 1 gamma 1 isozymes. The heterodimeric isozymes show intermediate effects, and the genetic polymorphism at the ADH3 locus is only discernible if electrophoresis is carried out in the presence of coenzyme. 3. The behaviour of the ioszymes can be attributed to slight differences between the products (alpha, beta 1 and gamma 1) of the common alleles at the three ADH loci and a pronounced difference between the products (gamma 1 and gamma 2) of the alternative alleles at the ADH3 locus in their affinities for the cofactor NAD.