Phenol hydroxylase acts a homodimer, to hydroxylates phenol to catechol or similar product. The enzyme is comprised of three domains. The first two domains from the active site. The third domain, this domain, is involved in forming the dimerisation interface. The domain adopts a thioredoxin-like fold [1].

1: The crystal structure of phenol hydroxylase in complex with FAD and phenol provides evidence for a concerted conformational change in the enzyme and its cofactor during catalysis. Enroth C, Neujahr H, Schneider G, Lindqvist Y; Structure 1998;6:605-617. PMID:9634698