Localization of bovine liver aldehyde dehydrogenase isozymes and their immunological properties

Evidence supporting the existence of three aldehyde dehydrogenases in bovine liver has been confirmed and the immunological properties of these isozymes have been compared. 1. The cytoplasmic and mitochondrial aldehyde dehydrogenases were distinguished in size by subjecting the bovine liver crude extract to Sephadex G-150 chromatog-raphy. The molecular weight of the cytoplasmic aldehyde dehydrogenase was determined to be 230, 000 daltons, larger than the mitochondrial enzyme by approximately 15, 000 daltons. 2. Submitochondrial fractionation indicated that the mitochondrial aldehyde dehydrogenase was located in the intermembrane space. 3. Anti-mitochondrial aldehyde dehydrogenase antibody from rabbit gave an im-munoreaction line not only with the mitochondrial enzyme but also with the cytoplasmic enzyme, and inhibited the activity of both enzymes. The anti-cytoplasmic aldehyde dehydrogenase antibody reacted with the cytoplasmic enzyme but had no effect on the mitochondrial enzyme. Neither antibody reacted with the micro-somal aldehyde dehydrogenase solubilized with sodium deoxycholate.