NADH Oxidation by Manganese Peroxidase with or without α-Hydroxy Acid

NADH oxidation by manganese peroxidase (MnP) was done in a reaction mixture including either α-hydroxy acid or acetate. The oxidation in the former reaction mixture was inhibited by a catalase and was accelerated by exogenous H 2 O 2 , while the oxidation in the latter reaction mixture was inhibited by a superoxide dismutase and was not accelerated by the exogenous H 2 O 2 . These results indicated that there are significant differences between the two reaction systems, particularly, in the active oxygen species involved in the reactions. Additionally, the experiment of MnP reduction with Mn(II) suggests that MnP has a separate catalytic activity other than an oxidation of Mn(II) to Mn(III) in the reaction mixture including acetate.