Interpretation of Fluctuation Spectra in Lipid Bilayer Simulations
Interpretation of Fluctuation Spectra in Lipid Bilayer Simulations
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DOI：
10.1016/j.bpj.2011.03.010
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发表时间：
2011-05-04
影响因子：
3.4
通讯作者：
Edholm, Olle
中科院分区：
文献类型：
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作者：
Brandt, Erik G.;Braun, Anthony R.;Edholm, Olle
使用完全基于傅立叶的方法分析了双肉豆蔻基磷脂酰胆碱脂双层的原子分辨率和粗粒度模拟中垂直于双分子层的波动。我们发现垂直于双层的运动的涨落谱可以分解为两部分：1)在小Q区占主导地位的与Q(-4)成正比的纯起伏谱；2)在大Q区占主导地位的分子密度结构因子贡献。不需要一个与Q(-2)成正比的项，它已被假设为凸起起伏，似乎是为了拟合中间Q的光谱所必需的。我们认为，早期关于这样一个项的报道是由于在获得傅立叶谱之前，在真实空间中进行入库和平滑的人工产物。基于测量和计算的材料常数，讨论了从涨落谱中观察到中间突出区的可观性。
Atomic resolution and coarse-grained simulations of dimyristoylphosphatidylcholine lipid bilayers were analyzed for fluctuations perpendicular to the bilayer using a completely Fourier-based method. We find that the fluctuation spectrum of motions perpendicular to the bilayer can be decomposed into just two parts: 1), a pure undulation spectrum proportional to q(-4) that dominates in the small-q regime; and 2), a molecular density structure factor contribution that dominates in the large-q regime. There is no need for a term proportional to q(-2) that has been postulated for protrusion fluctuations and that appeared to have been necessary to fit the spectrum for intermediate q. We suggest that earlier reports of such a term were due to the artifact of binning and smoothing in real space before obtaining the Fourier spectrum. The observability of an intermediate protrusion regime from the fluctuation spectrum is discussed based on measured and calculated material constants.