Water order profiles on phospholipid/cholesterol membrane bilayer surfaces.
Water order profiles on phospholipid/cholesterol membrane bilayer surfaces.
复制标题
磷脂/胆固醇膜双层表面的水序分布。
DOI：
10.1002/jcc.21840
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发表时间：
2011
影响因子：
3
通讯作者：
Robinson D
中科院分区：
文献类型：
--
作者：
Robinson D
水在大分子生物结构的稳定中起着关键作用，尽管水在分子表面附近的动态系综结构尚未完全了解。我们表明，通过分子模拟和荧光测量，在膜表面的水比散装水更有序，由于水分子之间的氢键的损失，再加上脂质和水的偶极矩的排列。水的有序化导致有效介电常数的梯度，这在分子模拟和荧光测量中都是明显的。在相同的空间范围内，较低的有效介电常数与氢键键合程度的降低相关。最接近脂质头基氧原子的水分子形成氢键，其平均寿命为6.3 ps，而水-水氢键的平均寿命小于2 ps。将纯由磷脂酰胆碱（PC）制成的膜与用与细胞膜相关的PC/胆固醇比率制成的膜进行比较。在这些膜配置之间发现了明显的差异。这些观察点膜的表面环境中的分子结构差异，并可能导致膜微区的表面生物物理性质的区域差异。© 2011 Wiley Periodicals，Inc. J Comput Chem，2011.
Water is pivotal in the stabilization of macromolecular biological structures, although the dynamic ensemble structure of water near to molecular surfaces has yet to be fully understood. We show, through molecular simulation and fluorescence measurements, that water at the membrane surface is substantially more ordered than bulk water, due to a loss of hydrogen bonding between water molecules, coupled with an alignment of lipid and water dipole moments. Ordering of the water leads to a gradient in the effective dielectric permittivity, which is evident in both the molecular simulations and the fluorescence measurements. A lower effective dielectric permittivity was correlated with a decreasing degree of hydrogen bonding over the same spatial range. The water molecules closest to the lipid headgroup oxygen atoms form hydrogen bonds which exhibit a mean lifetime of 6.3 ps, compared with a mean lifetime of water‐water hydrogen bonds of less than 2 ps. Membranes made up purely of phosphatidylcholine (PC) were compared with those made with a PC/cholesterol ratio relevant to cell membranes. Clear differences were found between these membrane configurations. These observations point to molecular structural differences in the surface environments of membranes and may underlie regional differences in the surface biophysical properties of membrane microdomains. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011.