Abstract
Cuticle-bound phenoloxidase was found in the pupae of the housefly (Musca domestica L.), and its properties were studied. The time course of dopachrome formation from dopa, and the effects of the amount of cuticles and dopa concentration on the formation of dopachrome from dopa by cuticle-catalyzed oxidation were studied. Cuticle-catalyzed oxidation was found to be an enzyme-catalyzed oxidation dependent on the cuticle-bound phenoloxidase. Km and Vmax values for the oxidation of dopa by cuticle-bound phenoloxidase were 4.70 mM and 1.68 × 10-2U/mg cuticle, respectively. The optimal temperature of cuticle-bound phenoloxidase was approximately 45°C, and it was stable between 5 and 25°C. The optimal pH of cuticle-bound phenoloxidase was approximately 9.0, and it was stable from pH 7.0 to 9.5.
