Activation kinetics of cetylpyridinium chloride on the prophenol oxidase from pupae of blowfly (Sarcophaga bullata)

Prophenol oxidase (PPO) (EC 1.14.18.1) is isolated from pupae of blowfly (Sarcophaga bullata) and purified by employing ammonium sulfate fractionation, ion-exchange chromatography on DEAE-cellulose, and gel filtration through Sephadex G-100 column chromatography. The enzyme exists in a latent or inactive state. Cetylpyridinium chloride (CPC), a cationic detergent, is found to activate the PPO activity. The activation of the enzyme by CPC has first been studied by using the kinetic method of the substrate reaction described by Tsou. The results show that the enzyme is activated by a complexing scheme that has not been previously identified. The enzyme first reversibly and quickly binds CPC and then undergoes a slow reversible active course. The activation reaction is a single molecule reaction and the apparent activation rate constant is dependent on the CPC concentration with the function relationship fit with a hyperbola. The micro rate constants of activation and the association constant are determined from the measurements. Substrate binding does not affect the micro rate constants of activation by CPC.