Laccase-type Phenoloxidase in the Cuticle of the Silkworm Bombyx mori

application/pdftextCuticular-bound phenoloxidase of the silkworm Bombyx mori was investigated in relation to the sclerotizing process that occurs following larval-pupal ecdysis. The phenoloxidase, having properties of laccase, seems to play an important role in the hardening and darkening process during the molting course, because of the correlation of these events with the change in the enzymatic activity. The enzyme was the laccase-type phenoloxidase judging from the substrate specificity. The phenoloxidase was in an inactive pro-form in newly ecdysed pupal cuticle and could be isolated with the aid of proteolysis. The pro-laccase could be activated by limited proteolysis. These results suggest that the pro-enzyme is activated by a proteolytic enzyme(s) which is present in the cuticle.departmental bulletin pape