The alpha subunit of the Class III extradiol dioxygenase, 2-amino-5-chlorophenol 1,6-dioxygenase, which catalyzes the oxidization and subsequent ring-opening of 2-amino-5-chlorophenol.
2-amino-5-chlorophenol 1,6-dioxygenase (2A5CPDO) catalyzes the oxidization and subsequent ring-opening of 2-amino-5-chlorophenol, which is an intermediate during p-chloronitrobenzene degradation. This enzyme is a member of 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. The active enzyme is probably a heterotetramer, composed of two alpha and two beta subunits. The alpha and beta subunits share significant sequence similarity and may have evolved by gene duplication. This model describes the alpha subunit, which does not contain a potential metal binding site and may not possess catalytic activity.