Substrate and inhibitor specificities of the thermostable alcohol dehydrogenase allozymes ADH-71k and ADH-FCh.D. of Drosophila melanogaster.

Purified thermostable alcohol dehydrogenase allozymes ADH-71k and ADH-FCh.D. of Drosophila melanogaster have been compared with the two common enzyme forms ADH-F and ADH-S. Enzyme kinetic parameters for various primary and secondary alcohols were determined under standard conditions used previously. Both ADH-71k and ADH-FCh.D. show ADH-S-like reaction kinetics and Km values, due to retrograde evolution at site 214, Pro-->Ser. Inhibition studies with alcohol dehydrogenase inhibitors pyrazole, 4-methylpyrazole, and cibacron blue 3GA were also performed. Activity measurements on crude extracts of larvae and flies from isogenic lines of ADH-FCh.D. revealed a consistently higher activity than in ADH-71k-containing strains, in contrast to the original strains.