菠萝蜜PPO与POD分离纯化、酶学性质及褐变抑制剂对其作用机理

Polyphenol oxidase(PPO) and peroxidase(POD)are key enzymes in browning of fruits and vegetables.No research on PPO and POD from the important tropical fruit-jackfruit has been reported yet.This project includes(1)analysis of activities and isoform changes of PPO and POD from jackfruit after harvest,understanding the relationship among browning,PPO and POD;(2)purification and enzymatic properties of PPO and POD from fruit;(3)determination of essential amino acid residues by chemical modification;(4)thermal inactivation kinetics of PPO and POD, calculation of kinetics constants,finding the optimum time and temperature during heat treatment;(5)inhibition of antibrowning reagents on PPO and POD,establishment of enzymatic inhibition kinetics model,exploring interaction between enzyme and substrate,regulation of enzyme,and relationship of structure and activity.. This project is not only a reference to explain the structure and function of PPO and POD, but also a guide for antibrowning of fresh-cut jackfruit and juice processing,and fruit storage and transportation.

多酚氧化酶PPO和过氧化物酶POD是果蔬褐变的重要酶。国内外尚无对菠萝蜜这一重要热带水果的PPO和POD的系统研究。本项目拟①对菠萝蜜采后果肉PPO和POD的酶活变化，PPO和POD同工酶酶谱的变化进行研究，了解褐变与PPO和POD的关系；②通过层析等步骤纯化得到果肉PPO和POD，研究其酶学性质；③运用化学修饰剂确定酶的活性必需氨基酸；④研究酶在高温处理时的动力学行为，测定热失活动力学参数，寻找最佳热处理时间和温度；⑤探讨褐变抑制剂对PPO和POD的抑制作用，建立酶抑制动力学模型，探索酶与效应物相互作用的分子机理、酶活力的调控机制和酶抑制剂的构效关系。.本项目不仅对阐明PPO和POD的酶学结构与功能等理论问题有重要的参考价值，还对采后菠萝蜜鲜切果加工、果汁加工、贮运过程中酶促褐变的控制等实际应用方面具有重要指导意义。

多酚氧化酶(PPO)和过氧化物酶(POD)是参与菠萝蜜褐变的主要酶。本项目通过层析等方法从菠萝蜜果肉中分别纯化出PPO和POD，通过酶学的方法对这两种酶进行了较为系统的研究，包括酶的分子量、等电点、底物特异性和催化机理、酶的耐热程度、酶的活性中心和必需基团，以及抑制剂对酶的作用。本研究还比较了几种抑制剂浸泡果肉后的实际效果，并观察了热处理灭酶活后果肉营养物质的损失，为菠萝蜜采后的保存运输与深加工提供了参考。发表了论文4篇，其中SCI论文1篇 (发表在Journal of Agricultural and Food Chemistry, IF 2.857, 农林科学1区)，中文核心论文3篇。