Adh-negative mutants: detection of an altered tryptic peptide in a mutant enzyme of Drosophila.

Adhnll is an ethyl methanesulfonate induced mutant that lacks detectable alcohol dehydrogenase activity. A number of indirect lines of evidence have indicated that the mutation responsible for this loss in enzyme activity is localized in the Adh structural gene. We present more direct evidence for this hypothesis here. Utilizing a newly developed procedure for comparing tryptic peptides of Drosophila alcohol dehydrogenase obtained from different strains, we show that the alcohol dehydrogenase-like protein isolated from Adhnll exhibits an altered peptide profile when compared to that of wild type. The implications of this finding as well as the utility of the method for attacking other genetic and developmental problems are discussed.