抄録
Aromatic acid reductase (aryl-aldehyde dehydrogenase, EC 1.2.1.30) was purified to electrophoretic homogeneity from Nocardia asteroides JCM 3016. The enzyme was a monomeric protein with a molecular weight of 152, 000. The enzyme absolutely required ATP, NADPH, and MgCl2 for the reduction of benzoate to benzaldehyde. In the overall reaction, benzaldehyde, AMP, and NADP+ were stoichiometrically formed from benzoate, ATP and NADPH, respectively. The purified enzyme catalyzed the reduction of benzoyl adenosine 5'-monophosphate (bzAMP), which is the intermediate formed from benzoate and ATP. The temperature dependence of the benzoate- and bzAMP-reducing activities agreed exactly, and the same Km for NADPH was obtained by the steady state kinetics of both reactions. These results suggest that the overall reduction of benzoate proceeds via bzAMP, and that the ATP-dependent adenylation of benzoate and the reduction of bzAMP are catalyzed by one enzyme. The enzyme was fairly specific for meta-substituted benzoates.
