Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, Canada.
Langmuir. 2012 Sep 11;28(36):12999-3007. doi: 10.1021/la301332e. Epub 2012 Aug 27.
A combination of vibrational sum frequency generation spectroscopy and atomic force microscopy is used to study the changes in morphology and conformational order in monolayers prepared from three natural sphingomyelin (SM) mixtures as a function of surface pressure and cholesterol concentration. The most homogeneous SM gave monolayers with well-ordered acyl chains and few gauche defects with relatively small effects of either increasing surface pressure or cholesterol addition. Heterogeneous SM mixtures with a mixture of acyl chain lengths or with significant fractions of unsaturated acyl chains had much larger contributions from gauche defects at low surface pressure and gave increasingly well-ordered monolayers as the surface pressure increased. They also showed substantial increases in lipid chain order after cholesterol addition. Overall, these results are consistent with the strong hydrogen bonding capacity of SM leading to well-ordered monolayers over a range of surface pressures. The changes in acyl chain order for natural SMs as a function of cholesterol are relevant to formation of sphingolipid-cholesterol enriched domains in cell membranes.
采用振动和频产生光谱学和原子力显微镜联用的方法，研究了三种天然神经鞘磷脂（SM）混合物单层在表面压力和胆固醇浓度变化时的形态和构象有序性变化。最均一的 SM 给出了具有有序酰基链和少量 gauche 缺陷的单层，其表面压力或胆固醇添加的影响相对较小。具有不同酰链长度或大量不饱和酰链的不均匀 SM 混合物在低表面压力时具有更大的 gauche 缺陷贡献，并且随着表面压力的增加，单层的有序性逐渐增加。加入胆固醇后，脂质链有序性也有显著提高。总的来说，这些结果与 SM 的强氢键能力一致，这种能力导致了在一定表面压力范围内的有序单层。天然 SM 中酰链有序性随胆固醇的变化与细胞膜中鞘脂-胆固醇富集域的形成有关。
