多酚氧化酶同工酶组成对茶黄素合成的影响

Effect of PPO Isoenzyme on Formation of Theaflavin during in vitro Oxidation

用垂直板聚丙烯酰胺凝的方法,研究了不同来源(茶叶、苹果、梨、蘑菇和漆酶)的多酚氧化酶同工酶的酶带特征。结果表明,不同来源多酚氧化酶同工酶具有相似的酶带,但对酶带数目、Rf值及分子量均存在种间差异。梨有11条同工酶带,苹果4条,茶叶有2条,蘑菇5条,而漆酶只有1条。PPO同工酶带Rf值集中于0.40～0.70的区间内。茶叶多酚氧化酶同工酶的相对分子量大于9.4×104,而梨、苹果、蘑菇和漆酶多酚氧化酶同工酶的相对分子量介于4.5×104～9.4×104。同时研究了多酚氧化酶活性和同工酶组成对茶黄素合成的影响。梨果实多酚氧化酶同工酶谱带最多,酶活性最大,合成茶黄素的能力最强。合成茶黄素能力大小顺序为:梨PPO,茶叶PPO,苹果PPO,漆酶PPO,蘑菇PPO。

The isoenzymes of polyphenol oxidase of different source （pear,apple,tea,mushroom and fungal lacease）were studied by means of the polyacrylamide gel vertical slab electrophoresis.Similar bands were observed in different source,but the number and width of the bands ＆ Rf value and molecular weight were different.11 bands of PPO activity were visible in pear extract. 4 bands of PPO activity were visible in apple extract. 2,5 and 1 bands were present in tea,mushroom extract and laccase,respectively.Rf value of PPO isoenzymes was between 0.40 and 0.70.Molecular weight of tea PPO isoenzymes was more than 94 000,while. that of pear, mushroom,apple and laccase PPO isoenzymes ranged from 45 000 to 94 000.An in vitro model fermentation system,containing tea catechins and crude pear polyphenol oxidase from different source has been used to determine the effect of PPO activity and isoenzyme forms on the formation of theaflavins. The bands of pear were more than that of others and its PPO activity is the highest.The ability to synthesis of theaflavins was in the order：pear PPO,tea PPO,apple PPO,laccase and mushroom PPO.