烟草多酚氧化酶固定化新工艺

引　言多酚氧化酶是一类广泛存在于自然界 (包括从细菌到哺乳动物 )的含铜蛋白 ,它们的共同特征是在分子氧存在下具有催化氧化酚到醌的能力1] .酚类物质及其衍生物的毒性和危害性以及它们在工业废水中含量日益增加的事实 ,已引起人们的重视2 ] .人们开始寻求用过氧化物酶或多

NEW TECHNOLOGY FOR IMMOBILIZATION OF POLYPHENOL OXIDASE FROM TOBACCO

Granule chitosan was prepared from chitosan,chemically-modified, then used as carrier and covalently linked with polyphenol oxidase(PPO) from tobacco by using glutaraldehyde as cross-linking agent.The desirable granule chitosan could be obtained when the molecular mass of chitosan was about 250000 and its concentration was about 30%.The absorbing ability and the category, distribution and number of active groups on the surface of granule chitosan were all improved by formol titration under weak basic condition after protecting parts of free amino-groups with Cu²⁺.The optimal conditions for immobilization of PPO were as follows: the ratio of PPO to granule chitosan: 0.8∶100(mass);concentration of glutaraldehyde:0.6%; immobilization time: 80 min.The resulting immobilized PPO had specific activity of 73 U•g^-1, and activity retention value of 83.2% was achieved.The K_m value of immobilized PPO was 4.67 mmol•L^-1 and that of soluble PPO was 1.26 mmol•L^-1.The optimal pH values were 6.0 for soluble PPO and 7.0 for immobilized PPO; the optimal temperature were 40 ℃ for soluble PPO and about 50 ℃ for immobilized PPO.In addition, stability of immobilized PPO to temperature and pH was obviously increased.