Collective and noncollective models of NMR relaxation in lipid vesicles and multilayers
Collective and noncollective models of NMR relaxation in lipid vesicles and multilayers
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DOI：
10.1021/jp075641w
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发表时间：
2008-05-15
影响因子：
3.3
通讯作者：
Pastor, Richard W.
中科院分区：
文献类型：
--
作者：
Klauda, Jeffery B.;Eldho, Nadukkudy V.;Pastor, Richard W.
NMR C-13自旋晶格弛豫（1/T-1）率的二棕榈酰磷脂酰胆碱（DPPC）双层从分子动力学模拟72和288脂质相互比较，从大脂质体魔角自旋获得的实验值，并与以前发表的实验数据从小泡。多层膜和囊泡在相同频率下的实验结果仅略有不同。模拟结果表明，在15.1至201.2 MHz的碳频率范围和高达100埃的长度尺度内，T-1弛豫由快速异构化和较慢的脂质摆动（D-垂直于约2.5 × 10（8）s（-1））主导。围绕脂质长轴的旋转扩散（由D-平行于描述）对T-1没有实质性贡献。用于模拟的酰基链扭转势能函数的修改大大提高与实验的一致性。
NMR C-13 spin lattice relaxation (1/T-1) rates of dipalmitoylphosphatidylcholine (DPPC) bilayers obtained from molecular dynamics simulations of 72 and 288 lipids are compared with each other, with experimental values from large liposomes obtained by magic angle spinning, and with previously published experimental data from small vesicles. The experimental results for multilayers and vesicles at the same frequencies differ only slightly. The simulation results indicate that T-1 relaxation in the 15.1 to 201.2 MHz carbon frequency range and up to 100 angstrom length scale is dominated by fast isomerizations and slower lipid wobble (D-perpendicular to approximate to 2.5 x 10(8) s(-1)). Rotational diffusion about the lipid long axis (described by D-parallel to) does not make a substantial contribution to the T-1. Modifications to the acyl chain torsional potential energy function used for the simulations substantially improve agreement with experiment.