Area per lipid and acyl length distributions in fluid phosphatidylcholines determined by 2H NMR spectroscopy
Area per lipid and acyl length distributions in fluid phosphatidylcholines determined by 2H NMR spectroscopy
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DOI：
10.1016/s0006-3495(00)76551-9
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发表时间：
2000-12-01
影响因子：
3.4
通讯作者：
Brown, MF
中科院分区：
文献类型：
--
作者：
Petrache, HI;Dodd, SW;Brown, MF
氘 (H-2) 核磁共振波谱提供有关脂质双层结构波动的详细信息，包括平衡特性和动力学。对具有全氘化饱和链（从 C12:0 到 C18:0）的同系系列 1,2-二酰基-sn-甘油-3-磷酸胆碱（从 C12:0 到 C18:0）的实验性 1H-2 NMR 测量已在随机取向、完全水合的多层样品上进行。对于每种脂质，C-D 键序参数是根据 de-Paked H-2 NMR 谱计算得出的，作为温度的函数。使用酰基链段分布的平均扭矩势模型分析了实验顺序参数，并与传统的金刚石晶格方法进行了比较。使用统计力学原理将测量的有序参数与脂质双层结构参数联系起来：烃厚度和每个脂质的平均界面面积。在固定温度下，面积随着酰基长度的增加而减小，表明对较长脂质链的范德华吸引力增加。然而，增加酰基链长度的主要影响是对烃的厚度而不是对每个脂质的面积。使用描述流体双层中的力平衡的经验自由能函数来报告和解释结构参数的膨胀系数。在相同的绝对温度下，磷脂酰胆碱 (PC) 系列表现出与磷脂酰乙醇胺 (PE) 不同的通用链堆积特征。因此，磷脂的侧向堆积对头基甲基化比对酰基链长度更敏感。使用经验自由能函数对 PC 系列的每个脂质面积进行拟合表明，PE 面积代表了流体酰基链堆积的极限值。
Deuterium (H-2) NMR spectroscopy provides detailed information regarding the structural fluctuations of lipid bilayers, including both the equilibrium properties and dynamics. Experimental H-2 NMR measurements for-the homologous series of 1,2-diacyl-sn-glycero-3-phosphocholines with perdeuterated saturated chains (from C12:0 to C18:0) have been performed on randomly oriented, fully hydrated multilamellar samples. For each lipid, the C-D bond order parameters have been calculated from de-Paked H-2 NMR spectra as a function of temperature. The experimental order parameters were analyzed using a mean-torque potential model for the acyl chain segment distributions, and comparison was made with the conventional diamond lattice approach. Statistical mechanical principles were used to relate the measured order parameters to the lipid bilayer structural parameters: the hydrocarbon thickness and the mean interfacial area per lipid. At fixed temperature, the area decreases with increasing acyl length, indicating increased van der Waals attraction for longer lipid chains. However, the main effect of increasing the acyl chain length is on the hydrocarbon thickness rather than on the area per lipid. Expansion coefficients of the structural parameters are reported and interpreted using an empirical free energy function that describes the force balance in fluid bilayers. At the same absolute temperature, the phosphatidylcholine (PC) series exhibits a universal chain packing profile that differs from that of phosphatidylethanolamines (PE). Hence, the lateral packing of phospholipids is more sensitive to the headgroup methylation than to the acyl chain length. A fit to the area per lipid for the PC series using the empirical free energy function shows that the PE area represents a limiting value for the packing of fluid acyl chains.