Kurganov B I, Shkarina T N, Malakhova E A, Davydov D R, Chebotareva N A
All-Union Vitamin Research Institute, Moscow, USSR.
Biochimie. 1989 Apr;71(4):573-8. doi: 10.1016/0300-9084(89)90189-2.
The rate of linoleic acid peroxidation catalysed by soybean lipoxygenase I was studied as a function of the hydration degree of aerosol OT (bis(2-ethylhexyl) sulfosuccinate sodium salt) reversed micelles in octane. Lipoxygenase reaction parameters for the micelle-bound substrate were spectrophotometrically determined. The linoleic acid distribution between the micelles and octane was detected by the sedimentation method, with the concentration of linoleic acid in supernatant after settling of micelles (i.e. the concentration of free linoleic acid) being estimated by the enzymatic method. The apparent constant of linoleic acid distribution (the ratio of the bound and free substrate concentrations) was enhanced with increasing hydration of reversed micelles. The dependence of the enzymatic reaction rate on the bound substrate concentration obeyed the empiric Hill equation. The Hill coefficient remained practically constant (h = 1.34) as the hydration degree changed. Parameters of the lipoxygenase reaction, enzyme reaction limiting rate V and semi-saturation substrate concentration [S]0.5 increased with increasing degree of hydration and reached the optimum at [H2O]/[AOT] approximately 30, where dimensions of the micellar internal cavity coincided with those of the enzyme molecule. Some aspects of kinetic behavior of membrane-bound enzymes participating in chemical transformation of non-polar compounds dispersed in lipid phase are discussed.
研究了大豆脂氧合酶I催化的亚油酸过氧化速率与辛烷中气溶胶OT（二（2-乙基己基）磺基琥珀酸钠盐）反胶束水合程度的关系。通过分光光度法测定了胶束结合底物的脂氧合酶反应参数。采用沉降法检测亚油酸在胶束和辛烷之间的分布，通过酶法估算胶束沉降后上清液中亚油酸的浓度（即游离亚油酸的浓度）。随着反胶束水合作用的增强，亚油酸分布的表观常数（结合底物浓度与游离底物浓度之比）增大。酶促反应速率对结合底物浓度的依赖性符合经验希尔方程。随着水合程度的变化，希尔系数实际上保持恒定（h = 1.34）。脂氧合酶反应的参数、酶反应极限速率V和半饱和底物浓度[S]0.5随着水合程度的增加而增加，并在[H2O]/[AOT]约为30时达到最佳值，此时胶束内腔尺寸与酶分子尺寸一致。讨论了参与脂质相中分散的非极性化合物化学转化的膜结合酶动力学行为的一些方面。
