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Steady state initial velocity studies were carried out to determine the kinetic mechanism of human liver aldehyde dehydrogenase. Intersecting double reciprocal plots obtained in the absence of inhibitors demonstrated that the dehydrogenase reaction proceeded by sequential addition of both substrates prior to release of products. Dead end inhibition patterns obtained with coenzyme and substrate analogues (e.g. thionicotinamide-AD+ and chloral hydrate) indicated that NAD+ and aldehyde can bind in random fashion. The patterns of inhibition by the product NADH and of substrate inhibition by glyceraldehyde were also consistent with this mechanism. However, comparisons between kinetic constants associated with the dehydrogenase and esterase activities of this enzyme suggested that most of the dehydrogenase reaction flux proceeds via formation of an initial binary NAD+-enzyme complex over a wide range of substrate and coenzyme concentrations.

A goat antibody against human renal-cell carcinoma reacted on immunofluorescence with renal-cell carcinomas from 20 patients, but not with normal adult human tissues, including kidney. After i.v. administration the I-131-linked antibody showed preferential tumor localization in six of seven patients with primary renal carcinoma. Labeled antitumor antibodies may have the specificity for tumor imaging that current radiopharmaceuticals lack.