Immobilization of Polyphenol Oxidase and Primary Study on Capacity to Remove the Diphenol
A copper-containing enzyme,polyphenol oxidase(short for PPO),has been isolated and purified with 215-fold and 23％ of recovery from apples by using acetone-emerged powder,extraction with phosphate buffer,centrifugation at low temperature,ammonium sulfate precipitation,and column chromatography on DEAE-Sephedex(A50),Sephadex(G-75), and DEAE-celluse(DE-52).Granulechitosan has been prepared deliberately from chitosan,then chemically-modified,and finally used as support and covalently linked with polyphenol oxidase(PPO) from apple by using glutaraldehyde as cross-linking agent.The results show that the desired granulechitosan could be obtained when molecular mass of chitosan was about 250 kDa,concentration of which was about 30％.The type,distribution and number of active groups on the surface of granulechitosan and the absorbing ability were all improved by formol titration under weak basic condition after protecting Darts of free amino-groups with Cu2+ The optimal conditions for the immobilization of PPO are as follow：the ratio of PPO to granulechitosan：1.0:125(w/w);concentration of glutaraldehyde:0.6％;immobilization time：80 min.The resulting immobilized PPO has a specific activity of 73U/g(support).and an activity retention value of 83.2％ has been reached.The Km value of immobilized PPO was higher than that of the native PPO.The optimal pH were 6.0 for native PPO and 7.0 for immobilized PPO;the optimal temperature were 40℃ for native PPO and about 50℃ for immobilized PPO.In addition,stabilities of immobilized PPO to both temperature and PH were obviously increased.
apple deacetylchitin glutaraldehyde immobilization polyphenol oxidase
XIAO Hourong WU Qianqian CAI Jingmin WU Ke WANG Zhongfeng ZHANG Jie YANG Hong
Department of Biological and Environmental Engineering,Hefei University,Hefei 230022,China;Key Labor Department of Biological and Environmental Engineering,Hefei University,Hefei 230022,China
国际会议
合肥
英文
495-500
2008-06-05（万方平台首次上网日期，不代表论文的发表时间）