NMR INVESTIGATIONS OF CELL MEMBRANE STRUCTURE

本研究的主要目的是：（1）研究 乙醇与蛋白质和脂质在生物膜中的作用;（2）研究 由脂质组成的膜的结构和动力学， 二十二碳六烯酸（DHA，22：6 n-3）等多不饱和脂肪酸; （3）研究与酒精中毒和脂质相关的脂质-蛋白质相互作用 多不饱和度 (1)乙醇在膜内的位置已经被 直接用二维NOESY和魔角旋转法研究 匪r 根据NOESY交叉口强度，我们确定乙醇存在于 在靠近脂质的脂质-水界面处的概率最高 甘油和脂烃链的上部亚甲基片段。 双层疏水核中的乙醇浓度显著增加。 低于(2)（2）使用1H NMR光谱来测量PC中的有序度， 一个全氘代硬脂酰基sn-1链和四个不饱和sn-2链， 18：1 n-9、18：2n-6、20：4 n-6和22：6 n-3 -与相同的PE组合 脂肪酸组成和胆固醇。 多不饱和双层是 与单不饱和和双不饱和双层的不同之处在于， 所有胆固醇浓度下的最低顺序， 通过PE。 多不饱和膜显示较少的乙醇诱导链 比单不饱和膜和双不饱和膜更无序。 一种改进的~（17）O NMR 提出了一种快速渗水的测量方法 通过脂质双层。 分子中的低级烃链序 多不饱和脂质似乎与较高的水渗透相关 通过多不饱和膜的速率。 乙醇的加入降低了 水渗透，很可能是通过限制水分子的进入 进入细胞膜。 (3)肽片段828-848具有序列 来自包膜羧基末端区域的RVIEVVQGACRAIRHIPRRIR HIV-1的糖蛋白gp 41深深地结合到带负电荷的 DMPC双层作为两亲性α-螺旋。 肽的测量 与特异性氘代异亮氨酸氨基酸的比较表明， 四个异亮氨酸残基中的三个深深地嵌入在 膜的碳氢化合物核心。 带正电荷的羧基 肽的末端位于双层表面，并显示出 更高的灵活性。

The objectives of this project are to: (1) investigate the interaction of alcohol with proteins and lipids in biological membranes; (2) study structure and dynamics of membranes composed of lipids with polyunsaturated fatty acids such as docosahexaenoic acid (DHA, 22:6n-3); and (3) study lipid-protein interactions related to alcoholism and lipid polyunsaturation. (1) The location of ethanol within a membrane has been investigated directly with two-dimensional NOESY and magic-angle-spinning NMR. From NOESY crosspeak intensities we determined that ethanol resides with highest probability at the lipid-water interface near the lipid glycerol and the upper methylene segments of lipid hydrocarbon chains. Ethanol concentration in the bilayer hydrophobic core is significantly lower. (2) (2)H NMR spectroscopy was used to measure order in PCs with a perdeuterated stearoyl sn-1 chain and four unsaturated sn-2 chains - 18:1n-9, 18:2n-6, 20:4n-6, and 22:6n-3 - combined with PE of identical fatty acid composition and cholesterol. The polyunsaturated bilayers are distinct from the mono- and diunsaturated bilayers in that they had the lowest order at all cholesterol concentrations and were the least ordered by PE. Polyunsaturated membranes show less ethanol-induced chain disorder than mono- and diunsaturated membranes. A modified (17)O NMR method has been developed for measurement of fast water permeation through lipid bilayers. The lower hydrocarbon chain order in polyunsaturated lipids appears to correlate with higher water permeation rates through polyunsaturated membranes. Addition of ethanol reduces water permeation, most likely by restricting entry of water molecules into the membrane. (3) The peptide fragment 828-848 with the sequence RVIEVVQGACRAIRHIPRRIR from the carboxy terminal region of the envelope glycoprotein gp41 of HIV-1 deeply incorporates into negatively charged DMPC bilayers as an amphipathic alpha-helix. Measurements on peptide with specifically deuterated isoleucine amino acids demonstrate that three of the four isoleucine residues are deeply imbedded in the hydrocarbon core of the membrane. The positively charged carboxy terminus of the peptide is located at the bilayer surface and shows a higher degree of flexibility.