The Action of Cytosolic Aldehyde Dehydrogenase on Resorufin Acetate

Abstract

Aldehyde dehydrogenase is well known to have the ability to act as an esterase as well as to catalyse the oxidation of aldehydes by NAD⁺. Some workers have been of the opinion that the twin activities of the enzyme are not closely related and occur at separate enzymic sites (see, for example, Motion et al., 1988), whereas we have thought for a number of years that the balance of evidence favours the simpler one-site model (see, for example, Kitson et al., 1991). Recently, the extensive studies of Klyosov et al. (1996) have rekindled the debate; these authors suggest that even within the dehydrogenase activity alone, separate sites are responsible for the oxidation of some substrates (such as acetaldehyde and 6-dimethylamino-2-naphthaldehyde) in human mitochondrial aldehyde dehydrogenase (though not in the cytosolic isozyme).