Purification and characterization of an l-amino acid oxidase from Pseudomonas sp. AIU 813

An l-amino acid oxidase was found from a newly isolated strain, Pseudomonas sp. AIU 813. This enzyme was remarkably induced by incubation with l-lysine as a nitrogen source, and efficiently purified using an affinity chromatography with l-lysine as ligand. The enzyme oxidized l-lysine, l-ornithine and l-arginine, but not other l-amino acids and d-amino acids. The oxidase activity for l-lysine was detected in a wide pH range, and its optimal was pH 7.0. In contrast, the oxidase activity for l-ornithine and l-arginine was not shown in acidic region from pH 6.5, and optimal pH for both substrates was 9.0. The enzyme was a flavoprotein and composed of two identical subunits with molecular mass of 54.5 kDa. The N-terminal amino acid sequence was similar to that of putative flavin-containing amine oxidase and putative tryptophan 2-monooxygenase, but not to that of l-amino acid oxidases.