Peroxisome-associated aldehyde dehydrogenase in normal rat liver

Abstract

We have combined subcellular fractionation and cytochemical staining techniques to study the distribution of aldehyde dehydrogenase in rat liver. In addition to confirming the mitochondrial and microsomal localization of aldehyde dehydrogenase, this combined approach has allowed us to demonstrate that peroxisome-like organelles possess significant aldehyde dehydrogenase. When peroxisomal fractions are cytochemically stained for aldehyde dehydrogenase, activity is observed along membranes of structures resembling peroxisomal ghosts. These bodies lack a matrix but many appear to enclose peroxisomal cores. Moderate to dense reaction product is also located in single membrane-limited structures present in fractions containing morphologically recognizable peroxisomes. On occasion, the osmiophilic precipitate is also present in the matrix of intact peroxisomes. The aldehyde dehydrogenase activity in these peroxisome-like organelles prefers aliphatic aldehydes, including acetaldehyde in both millimolar and micromolar concentrations, and NAD. Aromatic aldehydes and NADP are also metabolized, but to a lesser extent. These results indicate that peroxisome-like organelles contain an aldehyde dehydrogenase activity possessing properties compatible with a role in ethanol metabolism.