Subcellular localization and capacity of beta-oxidation and aldehyde dehydrogenase in porcine liver

Porcine hepatocyte organelles were separated by isopycnic sucrose gradient centrifugation from livers of 6-month-old Yorkshire pigs. The presence of a peroxisomal palmitoyl-CoA oxidizing system and a peroxisomal NAD:aldehyde dehydrogenase (ALDH) with high Km for acetaldehyde was demonstrated. Peroxisomal palmitate oxidizing capacity was found to be equal to that of the surviving mitochondria. The high Km isozyme of ALDH was mainly located in the mitochondria (54%), with a significant portion in the peroxisome (32%). Remaining activity is distributed among the microsomes (8.3%) and cytosol (4.6%). The low Km isozyme was confined almost exclusively to the mitochondria. ALDH may exist in the peroxisome as a detoxification mechanism and contribute to shorter half-lives of reactive aldehydes in the cell. Species differences are discussed.