Subcellular distribution and properties of rabbit liver aldehyde dehydrogenases

Abstract

In rabbit liver, both NAD +- and NADP +-dependent aldehyde dehydrogenases were identified. The activities were distributed among at least three major groups of isozymes identifiable by gel electrophoresis. These isozymes also differed in their substrate and coenzyme preferences, subcellular distributions, and/or responses to effectors. The NAD +-dependent aldehyde dehydrogenase activity was distributed among the mitochondrial, microsomal, and cytosolic fractions. The NADP +-dependent aldehyde dehydrogenase activity was largely microsomal, with little true cytosolic NADP +-dependent activity demonstrable. Aliphatic aldehydes were oxidized equally well by aldehyde dehydrogenases in all three fractions. Aromatic aldehydes, however, were preferentially oxidized by microsomal aldehyde dehydrogenases. Disulfiram significantly inhibited mitochondrial (45 per cent) and cytosolic (93 per cent) NAD +-dependent aldehyde dehydrogenase, but it did not cause significant inhibition of microsomal NAD +-dependent activity. Disulfiram inhibited the NADP +-dependent aldehyde dehydrogenase activity (>71 per cent) in all subcellular fractions. Diethylstilbestrol activated both NAD +- and NADP +-dependent aldehyde dehydrogenases in mitochondria and cytosol. Microsomal aldehyde dehydrogenases were not affected by diethylstilbestrol.