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arXiv 1307.0367cond-mat.softq-bio.BM
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成筏膜脂质的单层自发曲率

Monolayer Spontaneous Curvature of Raft-Forming Membrane Lipids

Benjamin Kollmitzer, Peter Heftberger, Michael Rappolt, Georg Pabst

摘要:

采用小角X射线散射(SAXS)在倒置六方相(HII)上获得胆固醇、DOPE、POPE、DOPC、DPPC、DSPC、POPC、SOPC和卵鞘磷脂的单层自发曲率。自发曲率的双层形成脂质的估计通过添加控制量的HII形成模板以下先前建立的协议。磷脂酰乙醇胺和胆固醇的自发曲率被发现至少是一个因素的两个更负的磷脂酰胆碱,其J 0更接近于零。有趣的是,DPPC在25 °C下获得了显著的正J 0值(+0.11/nm)。我们进一步确定了自发曲率J 0(T)在15 ~ 55 \degC范围内的温度依赖性,结果表明,大多数研究的脂质的自发曲率分布非常窄,为-1 ~-3 * 10^-3 l/nm°C。这些数据使我们能够估计单层自发曲率的三元脂质混合物显示液体有序/液体无序相共存。我们报告的自发曲率相图DSPC/DOPC/胆固醇,DPPC/DOPC/胆固醇和SM/POPC/胆固醇和蛋白质插入和线张力的影响进行了讨论。

英文摘要:

Monolayer spontaneous curvatures for cholesterol, DOPE, POPE, DOPC, DPPC, DSPC, POPC, SOPC, and egg sphingomyelin were obtained using small-angle X-ray scattering (SAXS) on inverted hexagonal phases (HII). Spontaneous curvatures of bilayer forming lipids were estimated by adding controlled amounts to a HII forming template following previously established protocols. Spontanous curvatures of both phosphatidylethanolamines and cholesterol were found to be at least a factor of two more negative than those of phosphatidylcholines, whose J0 are closer to zero. Interestingly, a significant positive J0 value (+0.1 1/nm) was retrieved for DPPC at 25 °C. We further determined the temperature dependence of the spontaneous curvatures J0(T) in the range from 15 to 55 \degC, resulting in a quite narrow distribution of -1 to -3 * 10^-3 1/nm°C for most investigated lipids. The data allowed us to estimate the monolayer spontaneous curvatures of ternary lipid mixtures showing liquid ordered / liquid disordered phase coexistence. We report spontaneous curvature phase diagrams for DSPC/DOPC/Chol, DPPC/DOPC/Chol and SM/POPC/Chol and discuss effects on protein insertion and line tension.

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