Acetonitrile induces nonsynchronous interdigitation and dehydration of dipalmitoylphosphatidylcholine bilayers.
Acetonitrile induces nonsynchronous interdigitation and dehydration of dipalmitoylphosphatidylcholine bilayers.
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DOI：
10.1021/jp104190z
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发表时间：
2010-09
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影响因子：
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通讯作者：
Fulin Wu;Nannan Wang;Le-Fu Tao;Zhi‐Wu Yu
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作者：
Fulin Wu;Nannan Wang;Le-Fu Tao;Zhi‐Wu Yu
交叉指状（L（β）I）相的形成机制和磷脂的各个基团对相变的响应是脂质研究领域内的基本关注。本文利用差示扫描量热法、同步辐射X射线衍射和傅里叶变换红外光谱研究了乙腈（CH（3）CN）对二棕榈酰磷脂酰胆碱（DPPC）双层膜结构和相行为的影响。我们发现，这两个过程（即，DPPC双层的交错和脱水）在两种不同的CH（3）CN浓度（4和12wt%）下不同步地发生。在c（CH（3）CN）= 4wt%时，L（β）I相在L（β ′）到L（β）I相转变过程中形成机理的详细亚分子图像被提供：脂质酰基链的构象状态和六方堆积方式以及脂质极性基团的水合性质没有改变，不同之处仅在于形成的L（β）I相比L（β ′）相具有更紧密的脂酰基链堆积。当c（CH（3）CN）> 12wt%时，添加的CH（3）CN分子选择性地使界面羰基脱水。因此，在c（CH（3）CN）含量分别为5-12和13- 40wt%的范围内，存在两种不同的L（β）I相，其差别仅在于磷脂界面羰基的水合状态不同。从乙腈毒性的角度讨论了乙腈诱导脂质双层中的交叉结合的强能力。
The formation mechanism of the interdigitated (L(β)I) phase and the responses of the individual groups of phospholipids to the phase transition are of basic concern within the community of lipid research. In this work, we studied the effect of acetonitrile (CH(3)CN) on the structure and phase behavior of dipalmitoylphosphatidylcholine (DPPC) bilayers by using differential scanning calorimetry, synchrotron X-ray diffraction, and Fourier transform infrared spectroscopy. We found that the two processes (i.e., the interdigitation and dehydration of the DPPC bilayers) occur nonsynchronously at two different CH(3)CN concentrations (4 and 12 wt %). A detailed submolecular picture for the formation mechanism of the L(β)I phase was provided during the L(β') to L(β)I phase transition at c(CH(3)CN) = 4 wt %: the conformation state and the hexagonal packing mode of the lipid acyl chains and the hydration properties of the lipid polar groups do not change, and the only difference is that the formed L(β)I phase has a tighter lipid acyl chain packing than that of the L(β') phase. When c(CH(3)CN) > 12 wt %, the added CH(3)CN molecules selectively dehydrate the interfacial carbonyl groups. Thus, two different kinds of L(β)I phases differing only in the hydration states of the interfacial carbonyl groups of phospholipids exist in the c(CH(3)CN) regions of 5-12 and 13-40 wt %, respectively. The strong ability of acetonitrile to induce interdigitation in the lipid bilayers has been discussed in the viewpoint of its toxicity.