Purification of an Aromatic Amine-dependent NAD(P)H Oxidase from Tomato Fruit and Its Characterization as a Peroxidase

Abstract

1. An aromatic amine-dependent NAD(P)H-oxidizing enzyme was purified from tomato fruit to homogeneity as judged by SDS-polyacrylamide gel electrophoresis. NAD(P)H was oxidized under aerobic conditions in the presence of aromatic amines such as N,N-dimethylaniline, N-methylaniline, and aniline. The amines were essential for the reaction, but were not metabolized.

2. The enzyme had a monomer molecular weight of 48,000. On the basis of its spectral characteristics and the inhibition by KCN, NaN₃, and catalase, the enzyme was identified as a protoheme peroxidase.