Purification and Characterization of a Lecithin-d(-)-β-Hydroxybutyrate Dehydrogenase Complex

Abstract

Abstract A complex between partially purified d(-)-β-hydroxybutyrate dehydrogenase from beef heart mitochondria and soybean lecithin was purified. The active complex contains a single type of polypeptide chain of molecular weight 32,000 as determined by sodium dodecyl sulfate-acrylamide gel electrophoresis. The amino acid composition of the polypeptide chain is similar to that of many soluble enzymes, despite the very strong interaction with lecithin vesicles which was demonstrated. Cross-linking experiments with dimethyl suberimidate dihydrochloride failed to disclose any polypeptide aggregates in the enzyme-lecithin complex. The apparent Michaelis constants for all four substrates and the temperature dependence of the initial velocity were determined for the purified complex.