Modulated phases of phospholipid bilayers induced by tocopherols
Modulated phases of phospholipid bilayers induced by tocopherols
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DOI：
10.1016/j.bbamem.2012.06.016
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发表时间：
2012-11-01
影响因子：
3.4
通讯作者：
Raghunathan, V. A.
中科院分区：
文献类型：
--
作者：
Kamal, Md Arif;Raghunathan, V. A.
用X射线衍射法研究了α-、γ-和δ-生育酚对二棕榈酰磷脂酰胆碱（DPPC）双层膜结构和相行为的影响。在所有三种情况下，发现DPPC的主转变温度（T-m）随着生育酚浓度的增加而降低，直到约25摩尔。超过此，在γ-生育酚的情况下，主转变被抑制，而在另外两种情况下，T-m变得对组成不敏感。发现在DPPC-γ-生育酚和DPPC-δ-生育酚双层膜中，在7.5和10摩尔%之间的窄生育酚浓度范围内，预转变被抑制，并且涟漪相在研究的最低温度下发生。在所有三种情况下，在生育酚浓度高于约10 mol%时观察到调制相，这与DPPC-胆固醇双层中报道的P-β相相似。这一阶段被发现发生，甚至在过量的水条件下，在较低的生育酚浓度，并与周期性的高度调制的双层组成。这些结果表明生育酚诱导膜局部弯曲的能力，这可能对它们的一些生物学功能很重要。(C)2012爱思唯尔有限公司版权所有。
The influence of alpha-, gamma- and delta-tocopherols on the structure and phase behavior of dipalmitoyl phosphatidylcholine (DPPC) bilayers has been determined from X-ray diffraction studies on oriented multilayers. In all the three cases the main-transition temperature (T-m) of DPPC was found to decrease with increasing tocopherol concentration up to around 25 molt Beyond this the main transition is suppressed in the case of gamma-tocopherol, whereas T-m becomes insensitive to composition in the other two cases. The pre-transition is found to be suppressed over a narrow tocopherol concentration range between 7.5 and 10 mol% in DPPC-gamma-tocopherol and DPPC-delta-tocopherol bilayers, and the ripple phase occurs down to the lowest temperature studied. In all the three cases a modulated phase is observed above a tocopherol concentration of about 10 mol%, which is similar to the P-beta phase reported in DPPC-cholesterol bilayers. This phase is found to occur even in excess water conditions at lower tocopherol concentrations, and consists of bilayers with periodic height modulation. These results indicate the ability of tocopherols to induce local curvature in membranes, which could be important for some of their biological functions. (C) 2012 Elsevier B.V. All rights reserved.