NMR is a sophisticated method for investigation of structure and dynamics of lipid and protein molecules in membranes. Vibrational spectroscopy is also powerful because of relatively high resolution and sensitivity, and easier access than NMR. A combined use of these spectroscopies could provide important insights into the membrane biophysics. A structural analysis of phosphatidylethanolamine (PE) bilayers in built-up films by infrared dichroism suggested that polar groups oriented parallel to the membrane surface. A Raman analysis of phosphatidylcholine (PC) revealed that the gauche conformation was preferred for the choline backbone not only in solid, but also in the gel and liquid-crystalline states. The polar group structure of DPPC bilayers in the liquid-crystalline state was determined by analyzing deuterium quadrupole splitting of the choline group and phosphorus chemical shift anisotropy of the phosphate group in combination with restriction of the gauche conformation of the choline group determined by Raman spectroscopy. This was an excellent complementarity of NMR and vibrational spectroscopies. The deuterium quadrupole splitting values mentioned above were found to change on addition of ions such as NaCl, CaCl2, and LaCl3, suggesting that a structural change takes place on ion binding and the polar group of PC works as an electric charge sensor of membranes. The ion-bound structure was determined by NMR using the restriction from Raman spectroscopy. The PN vector of phosphorylcholine group was inclined by 63° from the membrane surface, while the inclination was 18° in the ion-free form. The deuterium quadrupole splitting values and phosphorus powder patterns revealed that on mixing with phosphatidylglycerol (PG) or cardiolipin (CL), PC did not change its dynamic structure of the glycerol backbone, but PE did. The mixture of PE with PG or CL shared a new dynamic structure, suggesting their adaptive miscibility in the molecular level. PC was molecularly immiscible with any of PE, PG, and CL. The molecular miscibility would regulate not only interactions of proteins with mixed bilayers but also formation of asymmetric lipid membranes. Interactions of crown-ether (CE) modified artificial microbial peptides with phospholipid bilayers were investigated by NMR and FTIR. CE-modified 14-mers with one or two basic amino acid residues revealed position-specific selectivity for the suppression of calcein leakage from PC vesicles but did not for that from PG vesicles, suggesting that structures of the lipid polar groups play crucial roles in different responses of the vesicles to the positively charged peptides. Manipulation of the peptide-polar group interaction can be used for drug design.

中文翻译：

---

通过结合使用NMR和振动光谱学阐明了膜中磷脂的结构和动力学。

NMR是研究膜中脂质和蛋白质分子的结构和动力学的复杂方法。振动光谱法也具有强大的功能，因为它具有较高的分辨率和灵敏度，并且比NMR易于访问。这些光谱学的结合使用可以为膜生物物理学提供重要的见识。通过红外二色性对堆积膜中的磷脂酰乙醇胺（PE）双层膜的结构分析表明，极性基团的取向平行于膜表面。磷脂酰胆碱（PC）的拉曼分析表明，不仅在固体状态，而且在凝胶状态和液晶状态中，乳脂状构象均优选用于胆碱骨架。通过分析胆碱基团的氘四极分裂和磷酸盐基团的磷化学位移各向异性，并结合拉曼光谱法确定的胆碱基团的构象构象，确定了处于液晶态的DPPC双层的极性基团结构。这是NMR和振动光谱学的极佳互补性。发现上述氘四极分裂值在添加诸如NaCl，CaCl2和LaCl3之类的离子时发生变化，这表明离子键发生结构变化，PC的极性基团充当膜的电荷传感器。使用拉曼光谱法的限制，通过NMR确定离子结合的结构。磷酸胆碱基团的PN向量从膜表面倾斜63°，无离子形式的倾斜度为18°。氘的四极分裂值和磷粉末模式表明，与磷脂酰甘油（PG）或心磷脂（CL）混合时，PC不会改变其甘油骨架的动态结构，而PE会改变。PE与PG或CL的混合物具有新的动力学结构，表明它们在分子水平上具有适应性。PC与PE，PG和CL中的任何一种在分子上均不混溶。分子可混溶性不仅可以调节蛋白质与混合双层的相互作用，还可以调节不对称脂质膜的形成。通过NMR和FTIR研究了冠醚（CE）修饰的人工微生物肽与磷脂双层的相互作用。CE修饰的具有1个或2个基本氨基酸残基的14-聚体显示出抑制PC囊泡中钙黄绿素泄漏的位置特异性选择性，但没有抑制PG囊泡中的钙黄绿素泄漏，这表明脂质极性基团的结构在不同分子中起关键作用囊泡对带正电荷的肽的应答。肽-极性基团相互作用的操纵可用于药物设计。