镍介入下大豆脂氧酶的催化活性和构象变化研究

Changes of Catalytic Activity and Conformation of Soybean Lipoxygenase Mediated by Nickel

外源镍对大豆脂氧酶(LOX)催化甘油三亚油酸酯反应产率的影响较为明显,氢过氧化甘油三亚油酸酯的产率从15.2%降低至8.0%,但对亚油酸底物的过氧化产率影响很小。镍可使LOX酶的UV光谱在一定浓度范围内增强一倍,但对FS和CD光谱影响甚微,说明镍对LOX的构象影响较小,可能只发生在与镍作用的局部细小部位。镍未将LOX活性中心的铁置换出来,推测镍与LOX酶蛋白表面氨基酸序列的特定位点发生结合,从而改变其细微构象并进而影响其催化性能。

Exogenous nickel had an obvious effect on the yield of trilinolein catalyzed by soybean lipoxygenase(LOX),the yield of trilinolein hydroperoxide decreased from 15.2%to 8.0%.But it had little effect on the yield of linoleic acid hydroperoxide.Nickel can double the UV spectrum of LOX enzyme in a certain concentration range,but has little effect on FS and CD spectra,which shows Nickel has little effect on the conformation of LOX.It may only occur in local small parts interacting with nickel.Nickel does not replace the iron in the active center of LOX,it may be inferred that nickel LOX binds to the specific site of amino acid sequence on the surface of LOX enzyme protein,which changes its fine conformation and affects its catalytic performance.