An electrophoretically cryptic alcohol dehydrogenase variant in Drosophila melanogaster. III. Biochemical properties and comparison with common enzyme forms.

The biochemical properties of the heat-stable alcohol dehydrogenase variant ADH-FCh.D. have been investigated and compared with those of the two common enzyme forms ADH-F and ADH-S. The results show that ADH-F and ADH-S differ with respect to substrate specificity, their response to high concentrations of secondary alcohols and their apparent Michaelis constants for three alcohols in two different buffer systems. In all these tests the enzyme ADH-FCh.D. resembles ADH-S much more closely than ADH-F. It is concluded that if natural selection is to distinguish between the alleles AdhS and AdhFCh.D. then it most probably does so on the basis of the superior thermostability of ADH-FCh.D. The biochemical properties of all three enzymes are discussed in relation to the role of alcohol dehydrogenase in the exploitation of alcohol by D. melanogaster.