不同条件下荔枝多酚氧化酶活性的分析(英)

经硫酸铵盐析和ＳｅｐｈａｄｅｓＧ－１００，Ｑ－Ｓｅｐｈａｒｏｓｅ和ＰｈｅｎｙｌＳｅｐｈａｒｏｓｅ柱层析分别纯化后，得到了电泳均一的荔枝多酚氧化酶，荔枝多酚氧化酶在ＳＤＳ和ＣＡＴＢ存在下测得的酶活性略有降低，但在ＴｒｉｔｏｎＸ－１００下活性有所增加，丁酸等短链的脂肪酸对酶活性起抑制作用，而亚油酸等长链的不饱和脂肪酸则起促进作用，另外，荔枝多酚氧化酶活性还明显受ＦｅＳＯ４和ＳｎＣｌ２所抑制，但能补Ｃａ

ANALYSIS OF LYCHEE POLYPHENOL OXIDASE ACTIVITY UNDER DIFFERENT CONDITIONS

Lychee polyphenol oxidase was purified by ammonium sulfate fractionation,gel fiLtration and ion exchange chromatography. The enzyme was found to be homogenous by SDSPAGE and shown to be activated by divalent canons such as Mn2 and Ca2 and long chainfatty acids,especially those with a high degree of unstaturation,and was markedly inhibitedby FeSO4. and SnC12 and short chain fatty acids such as butyric acid using 4--methylcatechol assubstrate. A slight decrease or increase was observed by added sodium dodecyl sulfate(SDS), hexadecyltri-methylammonium bromide (CATs) or triton X-100, respectively. Furthermore the effect of divalent cations on the activity of polyphenol oxidase was analysed.The optimum conditions for the activation process produced by the divalent canons had beenexamined with respect to canon concentration and pll of the reaction medium. This activationhad also been studied with regard to the kinetic parameters of the enzyme,which half--activation constants were in the order of 0. 8 mmol/L for Mn2 and 1. 2 mmol/L for CaZ . The K.decreased and the Vma. increased when Mn' and Ca2 (5 mmol/L) were present.