An Electrophoretically Cryptic Alcohol Dehydrogenase Variant in Drosophila Melanogaster. I. Activity Ratios, Thermostability, Genetic Localization and Comparison With Two Other Thermostable Variants

Abstract
The alcohol dehydrogenase (ADH) variant ADH-FCh.D. has a secondary alcohol/primary alcohol activity ratio characteristic of ADH-S although it has an electrophoretic mobility inseparable from ADH-F. ADH-FCh.D. is distinguished from these 2 common ADH variants by being much more thermostable. Genetic analysis suggests that ADH-FCh.D. is specified by an allele at the Adh locus. Biochemical comparisons show that ADH-FCh.D. has the same electrophoretic mobility, activity ratio and thermostability as the 2 other heat-resistant variants which have been reported, ADH-F71K in Europe and ADH-Fr in North America. The geographically widespread distribution of a thermostable ADH variant within the ADH-F electrophoretic class indicates that it should be considered in attempts to explain the Adh polymorphism in natural populations.