* To whom correspondence should be addressed.
Received November 12, 1998; Revision received March 25, 1999
Catechol 1,2-dioxygenases of the ordinary ortho-cleavage pathway have been isolated from strains Rhodococcus rhodnii 135 and Rhodococcus rhodochrous 89 grown on phenol as the sole source of carbon and energy. The activities of the catechol 1,2-dioxygenases with 3- and 4-methylpyrocatechols were 1.3-1.5 times higher than those with pyrocatechol. The rate of oxidation of 3-chloropyrocatechol catalyzed by both enzymes was 20% of the rate of oxidation of unsubstituted pyrocatechol. The enzymes are homodimers composed of 37-kD subunits.
KEY WORDS: catechol 1,2-dioxygenases, purification, substrate specificity, Rhodococcus, phenol