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 identify and localize these polypeptides by immunoblotting and indirect immunofluorescence. Immunofluorescence staining showed the enzyme to be localized primarily in tissues of the tail region of the worm. Some reactivity was also observed in the epidermis of the mid-body, but none was seen in the head region. These immunofluorescence results were supported by immunoblotting experiments, which also showed that chloroperoxidase holoenzyme is localized in the tail. Immunological results were substantiated by the distribution of enzyme activity and the in vivo products of the chloroperoxidase, 4-bromophenol, 2,4-dibromophenol, and 2,4,6-tribromophenol. Chloroperoxidase is the principal enzyme involved in the production of bromoaromatics in N. lobatus. Localization of most of this enzyme in the tail region explains the detection of high levels of bromophenols in the tail, the most exposed portion of this head-down, deposit-feeding worm. This pattern of bromoaromatic distribution is consistent with the hypothesis that the worms produce these compounds as defensive chemicals against epifaunal predators.