Faure C, Tranchant J F, Dufourc E J
Centre de Recherche Paul Pascal, CNRS, Pessac, France.
Biophys J. 1996 Mar;70(3):1380-90. doi: 10.1016/S0006-3495(96)79696-0.
The comparative effect of cholesterol (CH) versus cholesterol sulfate (CS) on dimyristoylphosphatidylcholine (DMPC) membranes has been investigated by optical microscopy, freeze-fracture electron microscopy, x-ray diffraction, and solid state 2H and 31P nuclear magnetic resonance (NMR). The sulfate analogue extends the lamellar phase domain toward high water contents, and substitution of 30 mol % CH by CS in DMPC lamellae induces the trapping of 30 wt % additional water. The greater swelling of the CS-containing systems is evidenced by determination of lamellar repeat distances at maximal hydration: 147 +/- 4 A and 64 +/- 2 A in the presence of CS and CH, respectively. 2H-NMR of heavy water demonstrates that CS binds approximately 12 more water molecules at the interface than CH whereas NMR of deuterium-labeled DMPC chains reveals that 30 mol % CS orders the membrane as 15 mol % CH at high temperature and disorders much more than CH at low temperatures. The various effects of CS versus CH are discussed by taking into account attractive Van der Waals forces and repulsive steric/electrostatic interactions of the negatively charged sulfate group.
通过光学显微镜、冷冻断裂电子显微镜、X射线衍射以及固态2H和31P核磁共振（NMR）研究了胆固醇（CH）与胆固醇硫酸酯（CS）对二肉豆蔻酰磷脂酰胆碱（DMPC）膜的比较效应。硫酸酯类似物将片层相区域扩展至高含水量，并且在DMPC片层中用CS替代30 mol%的CH会导致额外捕获30 wt%的水。通过测定最大水合时的片层重复距离可以证明含CS体系的膨胀更大：在CS和CH存在下，分别为147±4 Å和64±2 Å。重水的2H-NMR表明，CS在界面处比CH多结合约12个水分子，而氘标记的DMPC链的NMR显示，30 mol%的CS在高温下使膜有序化程度与15 mol%的CH相同，在低温下比CH无序得多。考虑到带负电荷的硫酸酯基团的范德华引力和空间/静电排斥相互作用，讨论了CS与CH的各种效应。
