栗子多酚氧化酶催化动力学及抑制机理的研究

RESEARCH INTO CATALYTIC REACTION DYNAMICS OF CHESTNUTS POLYPHENOL OXIDASE AND ITS INHIBITION

用丙酮从栗子中提取多酚氧化酶， 用分光光度法测出酶催化反应的最佳条件是ｐＨ 值为６ ．３ ， 温度为２５ ℃， 反应活化能等于２４ ．３６ ｋＪ·ｍｏｌ－ １ ， 米氏常数ＫＭ＝ １ ．０５４ ×１０ － ２ｍｏｌ·Ｌ－１ ； 研究了八种抑制剂对酶活性的抑制作用，其中柠檬酸的抑制机理是属于可逆竞争性抑制， 求得与抑制有关的常数ＫＩ＝ １ ．３４ ×１０ － ２ｍｏｌ·Ｌ－ １ ，

This paper discusses the extraction of polyphenol oxidase out of chestnut by using acetone, the optimum condition of enzyme catalytic reaction measured by spectrophotometer being that when the pH value is 6.3,temperature is 25℃,the reaction activation enzyme is 24.36kJ·mol -1 ,and the Michaelis constant is 1.054×10 -2 mol·L -1 .This paper also deals with the inhibition of 8 kinds of inhibitors on the activity of the enzyme. Among these inhibitors, citric acid is reversible competitive inhibitor with K I=1.34×10 -2 mol·L -1 , which is significant and instructive to the preservation of fruit and vegetables.