LOCALIZATION OF THE CHLOROPEROXIDASE OF THE CAPITELLID POLYCHAETE NOTOMASTUS-LOBATUS

Antisera against the two constituent proteins of the chloroperoxidase enzyme of the capitellid polychaete Notomastus lobatus were used to id entify and localize these polypeptides by immunoblotting and indirect immunofluorescence. Immunofluorescence staining showed the enzyme to b e localized primarily in tissues of the tail region of the worm. Some reactivity was also observed in the epidermis of the mid-body, but non e was seen in the head region. These immunofluorescence results were s upported by immunoblotting experiments, which also showed that chlorop eroxidase holoenzyme is localized in the tail. Immunological results w ere substantiated by the distribution of enzyme activity and the in vi vo products of the chloroperoxidase, 4-bromophenol, 2,4-dibromophenol, and 2,4,6-tribromophenol. Chloroperoxidase is the principal enzyme in volved in the production of bromoaromatics in N. lobatus. Localization of most of this enzyme in the tail region explains the detection of h igh levels of bromophenols in the tail, the most exposed portion of th is head-down, deposit-feeding worm. This pattern of bromoaromatic dist ribution is consistent with the hypothesis that the worms produce thes e compounds as defensive chemicals against epifaunal predators.