Subcellular Distribution of Human Brain Aldehyde Dehydrogenase

Abstract

Two human brain surgery biopsies and 1 autopsy sample were subjected to subcellular fractionation. With 0.12 or 6 mM -acetaldehyde as substrate, about half of the total aldehyde dehydrogenase activity was found in the mitochondrial (+ synaptosomal) fraction and less activity in the cytosolic, nuclear and microsomal fractions. High-affinity activity was found only in the mitochondrial fraction. The enzyme in all fractions had a higher affinity for indole-3-acetaldehyde than for acetaldehyde. The kinetic data indicate the presence of several distinct aldehyde dehydrogenase isozymes that have ample capacity to oxidize both aliphatic and aromatic aldehydes in human brain.