Drosophila melanogaster alcohol dehydrogenase. Biochemical properties of the NAD+-plus-acetone-induced isoenzyme conversion

Abstract

The NAD+ + acetone-induced isoenzyme conversion of the Drosophila melanogaster AdhS alleloenzyme was studied. Absorption and fluorescence spectra as well as electrophoretic and kinetic methods show that the conversion process proceeds through three steps. Initially a binary enzyme-NAD+ complex is formed, followed by a ternary enzyme-NAD+-acetone complex with a KEO, Ac of 1.7 M. The last step is a rate-limiting irreversible process in which NAD+ and acetone are covalently linked to the enzyme. A Vm of 2.4 min-1 was obtained at pH 8.6.