CarBb is the B subunit of the Class III Extradiol ring-cleavage dioxygenase, 2-aminophenol 1,6-dioxygenase, which catalyzes the oxidization and subsequent ring-opening of 2-aminophenyl-2,3-diol.
CarBb is the B subunit of 2-aminophenol 1,6-dioxygenase (CarB), which catalyzes the oxidization and subsequent ring-opening of 2-aminophenyl-2,3-diol. It is a key enzyme in the carbazole degradation pathway isolated from bacterial strains with carbazole degradation ability. The enzyme is a heterotetramer composed of two A and two B subunits. CarB belongs to the class III extradiol dioxygenase family, a group of enzymes which use a non-heme Fe(II) to cleave aromatic rings between a hydroxylated carbon and an adjacent non-hydroxylated carbon. Although the enzyme was originally isolated as a meta-cleavage enzyme for 2'-aminobiphenyl-2,3-diol involved in carbazole degradation, it has also shown high specificity for 2,3-dihydroxybiphenyl.