PH Effects on Cytoplasmic Aldehyde Dehydrogenase from Sheep Liver

Abstract

Although studies on the effect of pH on aldehyde dehydrogenase have been carried out in a number of laboratories, the results of these studies do not give a complete picture of the mechanism of the aldehyde dehydrogenase catalyzed oxidation of propionaldehyde over an extended pH range. The enzyme catalyzed oxidation reaction at pH 7.0 and 7.6 is generally agreed to occur by the following ordered mechanism:

$$E \rightleftharpoons E.NA{D^ + } \rightleftharpoons E.NA{D^ + }.ALD \rightleftharpoons E.NADH.acyl \to *E.NADH \rightleftharpoons E.NADH \rightleftharpoons E$$

Scheme I At least at low propionaldehyde concentrations, the rate of the reaction is controlled by the slow conformational change which occurs during the release of NADH from the enzyme (Blackwell et al., 1987; Dickinson, 1985).