Two Catechol 1,2-Dioxygenases from an Aniline-assimilating Bacterium, Frateuria species ANA-18†

When Frateuria species ANA-18was grown on aniline, two catechol 1, 2-dioxygenases (CD I and CDII, EC 1.13.11.1) were found in a cell-free extract of the strain. CDI and CDII were separated from each other by DE-52 chromatography and purified to homogeneity by successive column chromatography. The molecular weights of CDI and CD II were 38, 000 and 36, 000, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. CD I contained 2 mol of sulfhydryl groups per mol of protein, but CDII did not have cysteine or cystine residues. CDI was more stable on the acidic side and against heating than CDII. The activity of CDI was inhibited by AgNO3, HgCl2, iodoacetic acid and p-chloromercuribenzoic acid, but that of CDII was not inhibited or was less affected by them because of the lack of sulfhydryl groups. CD I exhibited a high activity for the extradiol cleavage of 3-methylcatechol, and the ratio of intradiol to extradiol activity was 100:120.