猕猴桃果实中PME,PG及其抑制因子的研究(综述)

A Review of Pectinmethylesterase, Polygalacturonase and Their Inhibitors in Actinidia

本文综述了猕猴桃中的PME，PG在果实软化中的作用、分离提纯、性质和活力测定方法，以及这两种酶的抑制因子等方面的研究进展。PME与猕猴桃果实的软化无直接关系，可能是通过为PG准备作用底物而起间接的促进软化的作用。猕猴桃果实内PME的抑制因子是一种糖蛋白，仅对PME有专一性的抑制作用。猕猴桃采后PG活性的上升促进果胶物质的水解是导致猕猴桃果实软化的重要原因。猕猴桃果实中存在一种专一性的猕猴桃蛋白酶（Actinidin），能抑制PG的活性，该蛋白酶可被巯基乙醇和DTT等所激活，也可被leupeptin和PCMB所抑制。

The functions, isolation &. purifications, properties and activities of PMG, PG and their inhibitors in kiwi fruit Actinidia are reviewed in this paper. There is no direct relationship between the activity of PME and the softening of Actitinia, but PME may produce the substrate for PG so that to enhance the softening process indirectly. The inhibitor of PME in Actinidia is a glucoprotein and appears to be specific for PME. The increase of PG activity is the main factor to promote the distruction of pectin substance and therefore result in the softening of Actinidia after harvest. A specific inhibitor existed in Actinidia fruit that is named actinidin, which inhibits the activity of PG significantly. The activity of actinidin can be triggered by mercaptoethanol and DTT, and also be inhibited by leupeptin and PCMB.