Partial characterization of hepatic aldehyde dehydrogenase from the baboon

The activities, isozymic forms, response to disulfiram and some physical and kinetic properties of hepatic aldehyde dehydrogenase (A1DH, [EC.1.2.1.3]) from baboons were investigated. A1DH specific activity was greater in mitochondria than in cytosol but cytosolic A1DH was more sensitive to disulfiram than mitochondrial A1DH. Gel isoelectric focusing revealed three major isozyme groups focusing between pH 4 and 7, two in mitochondria and one in cytosol. Isozyme profile differences between control and ethanol-fed baboons appeared chiefly in the cytosol. Cytosolic A1DH from a control baboon was purified 42 fold with a 21% yield by ammonium sulfate fractionation, ion exchange chromatography, and affinity chromatography. The enriched enzyme displayed non-linear kinetics with 10% of the total activity having a Km of 0.3 microM and 90% having a Km of 160 microM. pH for optimum activity was 9.0, molecular weight 290,000 and, between pH 6.8 and 8.0, Mg++ ions inhibited the A1DH activity in the cytosol.