南果梨多酚氧化酶的研究

Studies on Polyphenol Oxidase in Flesh of Nanguo Pear

南果梨果肉中多酚氧化酶（PPO）氧化邻苯二酚的活性明显高于氧化愈创木酚和间苯二酚的活性。以邻苯二酚为底物时，其多酚氧化酶的最适pH值为6．0。以儿茶酚为底物的多酚氧化酶氧化产物在420nm处有吸收高峰。聚乙烯吡咯烷酮（PVP）加入量与南果梨果肉酚类含量比为40：3时，南果梨果肉多酚氧化酶呈最大活性。30℃下多酚氧化酶的活性大于40℃、20℃、10℃、0℃下以儿茶酚为底物的南果梨果肉的多酚氧化酶活性。0．1MVc和001MEDTA对南果梨果肉的多酚氧化酶活性有明显抑制作用。根据凝胶电泳分析，南果梨果肉多酚氧化酶同功酶有8条谱带。

The Polyphenol oxiduse in Nanguo pear flesh can oxidize catechol, Resorcinol and O-Methoxyphenol, but the activities of oxidizing Resorcinol and O-Methoxy phenol were.rather low the maximumPeak of the PPO was obsecved at pH6.0 with catechol as substrate. When the ratio of' pVp to phenols inamount was 40:3, in the flesh of Nanguo pear, the PPO obtained the highest activity. The activities ofpolypyenol oxidase were obviously inhibitted by 0.1M' Vc and 0.01M EDTA. According to the gelelectrophoresis analysis, eight bands of the isoenzymes of polyphenol oxidase in flesh of Nanguo pear wereexPressed.