COMPARISON OF THE LIPID ACYL CHAIN DYNAMICS BETWEEN SMALL AND LARGE UNILAMELLAR VESICLES
COMPARISON OF THE LIPID ACYL CHAIN DYNAMICS BETWEEN SMALL AND LARGE UNILAMELLAR VESICLES
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DOI：
10.1016/s0006-3495(92)81881-7
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发表时间：
1992-03-01
影响因子：
3.4
通讯作者：
CAFISO, DS
中科院分区：
文献类型：
--
作者：
LEPORE, LS;ELLENA, JF;CAFISO, DS
在两种具有显着不同曲率的脂质制剂中以相同的方式测量了C-13 NMR自旋晶格弛豫（T1）速率和C-13-H-1核奥弗豪瑟效应（NOE）。将在四种磁场强度下获得的T1时间与NOE一起沿着至脂质分子动力学的简单模型。结果表明，磷脂链的顺序和动力学几乎是相同的，在小的和大的单层囊泡在这些C-13-NMR研究采样的时间尺度。在实验误差范围内，表征酰基链内部运动幅度和速率的序参数和重取向相关时间对于链中间的亚甲基段是相等的，两种囊泡类型之间的序参数和相关时间的唯一显著差异很小，并且出现在酰基链的末端。在羰基端的顺序是略高于小泡比大泡，并在甲基端的顺序是略低于小泡。这表明，在更多的平面系统的酰基链表现出稍微平坦的顺序比在更高度弯曲的膜。使用相同的实验方法在小和大的囊泡系统提供了一个更可靠和准确的评估曲率对分子顺序的影响比以前已经获得。
C-13 NMR spin-lattice relaxation (T1) rates and C-13-H-1 nuclear Overhauser effects (NOEs) were measured in an identical fashion in two lipid preparations having dramatically different curvatures. The T1 times that were obtained at four magnetic field strengths were fit along with the NOEs to simple models for lipid molecular dynamics. The results indicate that phospholipid chain ordering and dynamics are virtually identical in small and large unilamellar vesicles at the time scales sampled by these C-13-NMR studies. The order parameters and reorientational correlation times that characterize the amplitudes and rates of internal acyl chain motions were equal within experimental error for the methylene segments in the middle of the chains, The only significant differences in order parameters and correlation times between the two vesicle types were small and appeared at the ends ot the acyl chains. At the carbonyl end the order was slightly higher in small vesicles than large vesicles, and at the methyl end the order was slightly lower for small vesicles. This indicates that in the more planar systems the acyl chains exhibit a slightly flatter order profile than in more highly curved membranes. The use of the same experimental approach in both small and large vesicle systems provided a more reliable and accurate assessment of the effect of curvature on molecular order than has been previously obtained.