THE 2,4-DICHLOROPHENOL HYDROXYLASE OF ALCALIGENES-EUTROPHUS JMP134 ISA HOMOTETRAMER

2,4-Dichlorophenol hydroxylase (DCP-hydroxylase) is a key enzyme in th e pathway for degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in many bacteria. In Alcaligenes eutrophus JMP134, DCP-hydroxylase was r eported to consist of two dissimilar types of subunit of 66 and 45 kDa , a structure which is different from that in other bacteria. Using a different procedure involving affinity purification and ion-exchange c hromatography, we have purified active enzyme from JMP134 and show tha t it has a native molecular mass of approximately 245 kDa and consists of a single type of subunit of 66 kDa, similar to all other flavoprot ein monooxygenase enzymes. A 45-kDa polypeptide, found in partially pu rified enzyme preparations, was not required for enzyme activity but h ad some serologic and N-terminal amino acid sequence similarity to the 66-kDa enzyme subunit.