Yedgar S, Cohen R, Gatt S, Barenholz Y
Biochem J. 1982 Mar 1;201(3):597-603. doi: 10.1042/bj2010597.
The enzymic hydrolysis of three synthetic sphingomyelins, spread as monomolecular films at the air/water interface by purified Staphylococcus aureus sphingomyelinase was studied. Each of the three sphinomyelins (DL-erythro-N-palmitoyl-, -N-stearoyl- and -N-lignoceryl-sphingosylphosphocholine) has an optimal activity-dependent surface pressure or concentration curve. The optimal surface pressure as well as the optimal surface density for hydrolysis was different for each of the three substrates. This optimum coincides with the liquid-condensed/liquid-expanded phase transition for each of the sphingomyelins. At initial surface pressures (pi 0) below the optimum, reaction rates are controlled mainly by surface density of the substrate; above the optimal pi 0, reaction rates decrease with increasing surface pressure. The difference between the three synthetic sphingomyelins are explained by the variation in the degree of asymmetry between their two paraffinic chains.
研究了由纯化的金黄色葡萄球菌鞘磷脂酶在空气/水界面铺展成单分子膜的三种合成鞘磷脂的酶促水解作用。三种鞘磷脂（DL-赤藓糖-N-棕榈酰基-、-N-硬脂酰基-和-N-木质酰基-鞘氨醇磷酸胆碱）中的每一种都有一条最佳活性依赖的表面压力或浓度曲线。三种底物中每一种的水解最佳表面压力以及最佳表面密度都不同。这种最佳状态与每种鞘磷脂的液-凝聚/液-膨胀相变相吻合。在低于最佳值的初始表面压力（pi 0）下，反应速率主要由底物的表面密度控制；高于最佳pi 0时，反应速率随表面压力增加而降低。三种合成鞘磷脂之间的差异可通过其两条链烷链之间不对称程度的变化来解释。
