COMPARISON OF BETA-CYCLODEXTRIN EFFECT ON POLYPHENOL OXIDATION CATALYZED BY PURIFIED POLYPHENOL OXIDASE FROM DIFFERENT SOURCES

The effects of beta-cyclodextrin (beta-CD) on polyphenol oxidation cat alyzed by apple polyphenol oxidase (PPO), endive PPO, or mushroom tyro sinase have been compared. beta-CD forms a complex with phenolic subst rates of PPO by inclusion. Assuming a 1:1 beta-CD/phenol stoichiometry , and assuming that PPO is inactive on the complex beta-CD/phenol, K-D values were similar when determined kinetically by inhibition of appl e PPO or endive PPO. However, the experimental velocities found during inhibition of mushroom tyrosinase by beta-CD were higher than the val ues predicted by this model. In this latter case? it was assumed that mushroom tyrosinase is able to act on the complex beta-CD/ phenol. A n ew model based on this assumption allows experimental and calculated v elocities to be fit in presence of beta-CD.