Biochemical differences between products of the Adh locus in Drosophila

An analysis of the molecular properties of the major alcohol dehydrogenase (E.C.1.1.1.1.) allozyme variants found segregating in natural populations of D. melanogaster is presented. Our results indicate: (1) ADH-S enzyme has generally lower Michaelis-Menten constants than those of ADH-F; (2) ADH-S and ADH-F enzymes display opposite interactions for both co-factor and substrate; and (3) higher levels of ADH are associated with the Adh-fast genotype. The possible adaptive significance of these findings is discussed.