生命金属离子对漆酶催化活性的影响

The Influence of Catalyzed Activity of Laccase by Lives Metal Ions

以５，６二氯２，３二氰基氢醌为底物，在ｐＨ＝４．４０条件下，用分光光度法考察了１１种生命金属离子（Ｎａ＋、Ｋ＋、Ｃａ２＋、Ｍｇ２＋、Ｍｎ２＋、Ｆｅ２＋、Ｃｏ２＋、Ｃｕ２＋、Ｃｒ６＋、Ｎｉ２＋、Ｚｎ２＋）存在下的漆酶催化氧化反应，发现Ｆｅ２＋离子对漆酶的催化活性显示出抑制作用，探讨了其抑制特征、抑制位点和作用方式．结果表明，Ｆｅ２＋离子对漆酶催化活性抑制属竞争性抑制过程，Ｆｅ２＋离子的抑制作用是通过还原漆酶反应产物半醌自由基阴离子来完成的．Ｆｅ２＋离子漆酶复合物的解离常数（Ｋｉ）经测定为１７．５×１０－６ｍｏｌ·Ｌ－１．

The laccase catalyzed oxidation of eleven lives metal ions (Na + 、K +、Ca 2+ 、Mg 2+ 、Mn 2+ 、Fe 2+ 、Co 2+ 、Cu 2+ 、Cr 6+ 、Ni 2+ 、Zn 2+ ) were studied spectrophotometryly with 5,6 dichloro 2,3 dicyanohydroquinone under condition of pH=4.40.The studies showed that Fe 2+ ion had the inhibition action on catalytic activity of rhus laccase,and the inhibition of Fe 2+ ion was competitive and time dependent and the inhibited position was reducing the product of enzymatic reaction.The dissociation constant (K i) of complexed reaction of Fe 2+ ion with rhus laccase was 17.5×10 -6 mol·L -1 in pH=4.40 condition