Alcohol dehydrogenase of Drosophila melanogaster: metabolic differences mediated through cryptic allozymes.

Acetone formation from propan-2-ol, a saturated secondary alcohol, has been analysed in flies of three different Adh-genotypes of D. melanogaster. The in vivo oxidation of propan-2-ol was mainly mediated through ADH activity. It could be demonstrated that flies homozygous for the Adh71k allele produced more acetone than flies homozygous for AdhF. This difference in metabolic flux mediated through the cryptic allozymes under non-saturated ADH-substrate conditions seems to be based on their different kinetic properties in vivo. Product inhibition of ADH monitored by means of ADH-isozymes conversion as observed after electrophoresis was similar for both cryptic allozymes. ADH-71k and ADH-F showed immunological identity, and the in vivo protein levels of ADH-71k were 25-30 per cent higher than ADH-F. The population-genetic implications of our findings have been evaluated.