Microbial metabolism of quinoline and related compounds. XIII. Purification and properties of 1H-4-oxoquinoline monooxygenase from Pseudomonas putida strain 33/1.

1H-4-Oxoquinoline monooxygenase was purified to homogeneity from Pseudomonas putida strain 33/1 which can use 1H-4-oxoquinoline as sole source of carbon and energy. The apparent M(r) of the native enzyme was determined to be 126,000 by gel chromatography. SDS polyacrylamide gel electrophoresis of the enzyme revealed one protein band corresponding to M(r) 42,000. The enzyme consists of three probably identical subunits with a relative molecular mass of about 42,000. The enzyme requires oxygen and NADH for the reaction and is significantly inhibited by metal ions like Cu2+, Zn2+, Hg2+. The enzyme is specific only for 1H-4-oxoquinoline and the Km values of the enzyme for NADH and 1H-4-oxoquinoline were determined to be 87 microM and 25 microM, respectively.