Aldehyde dehydrogenase from human erythrocytes: structural relationship to the liver cytosolic isozyme

Human red cell aldehyde dehydrogenase (ALDH) resembles the liver cytosolic isozyme in numerous physicochemical properties. This study was undertaken to establish the structural relationship between the erythrocyte and liver ALDH isozymes. The purified red cell ALDH was S-(14C)-carboxymethylated, and cleaved with trypsin. The tryptic digest was fractionated using Sephadex and reversed-phase chromatography. All peptides analyzed were identified within the liver cytosolic enzyme structure. In each case the sequence obtained corresponds exactly to a segment from the human liver cytosolic ALDH. Thus, the erythrocyte enzyme, by virtue of its chemical and structural identity with the liver cytosolic enzyme, may serve as a suitable peripheral enzyme model to understand the cause and mechanism of alcohol abuse-related changes in liver cytosolic ALDH that has been found to be reduced in alcoholics.