ABSTRACT
Acetaldehyde, propionaldehyde, glyceraldehyde-3-P and 4-dimethylaminocinnamaldehyde form Schiff bases in Tris. HCl buffers; the rates of formation and dissociation of Schiff bases, and equilibrium constants for their formation are very similar for the first three aldehydes. The steady-state kinetic constants for the yeast alcohol dehydrogenase-catalyzed reaction, propan-1-ol + NAD+ reversible propionaldehyde + NADH + H+, have been determined in several Tris. HCl buffers of increasing concentration at pH 8.1. In the forward direction, oxidation of alcohol, most kinetic constants are increased by increasing concentrations of Tris. In the reverse direction, reduction of aldehyde, substrate, NADH, Tris and Schiff base were equilibrated before enzyme reaction was started. It was found that Schiff base, rather than Tris, binds to free enzyme competitively with respect to NADH. Tris and Schiff base do not influence the binding of aldehyde to enzyme in any way.
Subject(s)
Alcohol Dehydrogenase/chemistry , Alcohol Dehydrogenase/metabolism , Saccharomyces cerevisiae/enzymology , Tromethamine/chemistry , 1-Propanol/chemistry , 1-Propanol/metabolism , Acetaldehyde/chemistry , Acetaldehyde/metabolism , Acridines/chemistry , Acridines/pharmacology , Alcohol Dehydrogenase/drug effects , Aldehydes/chemistry , Aldehydes/metabolism , Buffers , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Kinetics , NAD/chemistry , NAD/metabolism , Oxidation-Reduction , Phosphates/chemistry , Potassium Compounds/chemistry , Tromethamine/pharmacologyABSTRACT
4-Dimethylamino-trans-cinnamaldehyde and chloroacetaldehyde are novel substrates of yeast alcohol dehydrogenase (EC 1.1.1.1). In the present work, we have reported the steady-state kinetic constants for both substrates, and their chemical reactions with the enzyme protein itself. Both substrates are potentially useful for biotechnology, chemoenzyme syntheses and analytical biochemistry.
