Asymmetric distribution of cone-shaped lipids in a highly curved bilayer revealed by a small angle neutron scattering technique
Asymmetric distribution of cone-shaped lipids in a highly curved bilayer revealed by a small angle neutron scattering technique
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小角中子散射技术揭示了高度弯曲双层中锥形脂质的不对称分布
DOI：
10.1088/0953-8984/23/28/284104
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
and M. Imai
中科院分区：
文献类型：
--
作者：
Y. Sakuma;N. Urakami;T. Taniguchi;and M. Imai
我们研究了由锥形（1, 2-二己酰基-sn-甘油-3-磷酸胆碱：DHPC）和圆柱形（1, 2-二棕榈酰-sn-甘油-3-磷酸胆碱：DPPC）脂质组成的二元小单层囊泡（SUV）中的脂质分选。为了揭示脂质分选，我们采用了小角中子散射（SANS）对比匹配技术，该技术定量提取双层中氘化脂质的分布，而无需像荧光探针技术那样对脂质进行空间修饰。首先，质子化 SUV 在薄膜对比条件下的 SANS 曲线显示，SUV 具有球形形状，内半径为 190 Å，双层厚度为 40 Å。氘化 SUV 在对比匹配条件下的 SANS 曲线显示出特征散射曲线，表明双层中锥形脂质的不对称分布。球形双层模型很好地描述了特征轮廓。拟合显示大多数 DHPC 分子位于外叶中。因此，脂质的形状与膜曲率密切相关。我们将获得的双层中锥形脂质的不对称分布与基于曲率能量模型的理论预测进行了比较。
We have investigated the lipid sorting in a binary small unilamellar vesicle (SUV) composed of cone-shaped (1, 2-dihexanoyl-sn-glycero-3-phosphocholine: DHPC) and cylinder-shaped (1, 2-dipalmitoyl-sn-glycero-3-phosphocholine: DPPC) lipids. In order to reveal the lipid sorting we adopted a contrast matching technique of small angle neutron scattering (SANS), which extracts the distribution of deuterated lipids in the bilayer quantitatively without steric modification of lipids as in fluorescence probe techniques. First the SANS profile of protonated SUVs at a film contrast condition showed that SUVs have a spherical shape with an inner radius of 190 Å and a bilayer thickness of 40 Å. The SANS profile of deuterated SUVs at a contrast matching condition showed a characteristic scattering profile, indicating an asymmetric distribution of cone-shaped lipids in the bilayer. The characteristic profile was described well by a spherical bilayer model. The fitting revealed that most DHPC molecules are localized in the outer leaflet. Thus the shape of the lipid is strongly coupled with the membrane curvature. We compared the obtained asymmetric distribution of the cone-shaped lipids in the bilayer with the theoretical prediction based on the curvature energy model.