MICROBIAL-METABOLISM OF QUINOLINE AND RELATED-COMPOUNDS .7. QUINOLINE OXIDOREDUCTASE FROM PSEUDOMONAS-PUTIDA - A MOLYBDENUM-CONTAINING ENZYME

The quinoline oxidoreductase from Pseudomonas putida was purified 50-fold to homogeneity with 21% recovery, using ammonium sulfate precipitation, hydrophobic interaction-, anion exchange-, and gel chromatography. The M(r) of the native enzyme was calculated to be 300 000 by gel filtration. SDS-polyacrylamide gel electrophoresis of the enzyme revealed three protein bands corresponding to M(r)85 000, 30 000 and 20 000. The enzyme contained 8 atoms of iron, 8 atoms of acid-labile sulfide, 2 molecules of FAD, and the molybdenum cofactor, molybdopterin. Besides quinoline, the quinoline oxidoreductase also catalysed the conversion of 5-, 6-, 7- and 8-hydroxyquinoline and 8-chloroquinoline to the corresponding 2-oxo compounds. The incorporated oxygen atom was derived from water. Cyanide and methanol were effective inhibitors.