STUDIES OF THE CATABOLIC PATHWAY OF DEGRADATION OF NITROBENZENE BY PSEUDOMONAS PSEUDOALCALIGENS JS45 - REMOVAL OF THE AMINO GROUP FROM 2-AMINOMUCONIC SEMIALDEHYDE

Pseudomonas pseudoalcaligenes JS45 utilizes nitrobenzene as the sole s ource of nitrogen, carbon, and energy. Previous studies have shown tha t degradation of nitrobenzene involves the reduction of nitrobenzene t o nitrosobenzene and hydroxylaminobenzene, followed by rearrangement t o 2-aminophenol, which then undergoes meta ring cleavage to 2-aminomuc onic semialdehyde. In the present paper, we report the enzymatic react ions responsible for the release of ammonia after ring cleavage. 2-Ami nomuconic semialdehyde was oxidized to 2-aminomuconate in the presence of NAD by enzymes in crude extracts. 2-Aminomuconate was subsequently deaminated stoichiometrically to 4-oxalocrotonic acid. No cofactors a re required for the deamination. Two enzymes, 2-aminomuconic semialdeh yde dehydrogenase and a novel 2-aminomuconate deaminase, distinguished by partial purification of the crude extracts, catalyzed the two reac tions. 4-Oxalocrotonic acid was further degraded to pyruvate and aceta ldehyde. The key enzyme, 2-aminomuconate deaminase, catalyzed the hydr olytic deamination that released ammonia, which served as the nitrogen source for growth of the organism.