Abstract
The initial reactions in the oxidation of naphthalene by Pseudomonas sp. strain NCIB 9816 involves the enzymatic incorporation of one molecule of oxygen into the aromatic nucleus to form (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. The enzyme catalyzing this reaction, naphthalene dioxygenase, was resolved into three protein components, designated A, B, and C, by DEAE-cellulose chromatography. Incubation of naphthalene with components A, B, and C in the presence of NADH resulted in the formation of (+)-cis-(1R,2S)-dihydroxy-1,2-dihydronaphthalene. The ratio of oxygen and NADH utilization to product formation was 1:1:1. NADPH also served as an electron donor for naphthalene oxygenation. However, its activity was less than 50% of that observed with NADH. Component A showed NAD(P)H-cytochrome c reductase activity which was stimulated by the addition of flavin adenine dinucleotide and flavin mononucleotide. A similar stimulation was observed when these flavin nucleotides were added to the naphthalene dioxygenase assay system. These preliminary observations indicate that naphthalene dioxygenase has properties in common with both monooxygenase and dioxygenase multicomponent enzyme systems.