Lipid Fluid-Gel Phase Transition Induced Alamethicin Orientational Change Probed by Sum Frequency Generation Vibrational Spectroscopy.
Lipid Fluid-Gel Phase Transition Induced Alamethicin Orientational Change Probed by Sum Frequency Generation Vibrational Spectroscopy.
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DOI：
10.1021/jp4047215
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发表时间：
2013-08-20
期刊：
影响因子：
--
通讯作者：
Chen Z
中科院分区：
文献类型：
--
作者：
Yang P;Wu FG;Chen Z
阿拉梅辛作为一种抗菌肽 (AMP) 已被广泛研究，并被广泛用作离子通道蛋白的简单模型。研究表明，AMPs的抗菌活性与其细胞膜取向有关，这可能受到细胞膜中脂质分子相位的影响。 “健康”的细胞膜含有流体相脂质，而凝胶相脂质可以在受伤或老化的细胞或某些相分离的膜区域中找到。因此，研究脂质的相如何影响 AMP 的膜方向对于了解有关 AMP 对细胞膜作用的更多细节非常重要。在这项研究中，我们使用和频生成（SFG）振动光谱确定了与不同相（流体或凝胶）的平面基质支持的单个脂质双层（作为模型细胞膜）相关的阿拉甲辛分子的方向变化，作为肽浓度的函数。脂质双层的相变是通过改变样品温度来实现的。我们的 SFG 结果表明，当脂质双层与低浓度 0.84 μM 的肽溶液接触时，阿拉甲辛沉积在流体和凝胶相 1,2-二肉豆蔻酰 (d54)-sn-甘油-3-磷酸胆碱 (d-DMPC) 脂质双层的表面。然而，在 10.80 μM 的中等肽浓度下，阿拉甲霉素会插入液相脂质双层中。当脂质双层的相从流体状态变为凝胶状态时，其方向从跨膜方向转变为面内（或平躺）方向。 At a high peptide concentration of 21.60 μM, alamethicin adopts a transmembrane orientation while associated with both fluid and gel phase lipid bilayers. We also studied the structural changes of the fluid and gel phase lipid bilayers upon their interactions with alamethicin molecules at different peptide concentrations.
Alamethicin has been extensively studied as an antimicrobial peptide (AMP) and is widely used as a simple model for ion channel proteins. It has been shown that the antimicrobial activity of AMPs is related to their cell membrane orientation, which may be influenced by the phase of the lipid molecules in the cell membrane. The “healthy” cell membranes contain fluid phase lipids, while gel phase lipids can be found in injured or aged cells or in some phase separated membrane regions. Thus, investigations on how the phase of the lipids influences the membrane orientation of AMPs are important to understand more details regarding the AMP’s action on cell membranes. In this study, we determined the orientational changes of alamethicin molecules associated with planar substrate supported single lipid bilayers (serving as model cell membranes) with different phases (fluid or gel) as a function of peptide concentration using sum frequency generation (SFG) vibrational spectroscopy. The phase changes of the lipid bilayers were realized by varying the sample temperature. Our SFG results indicated that alamethicin lies down on the surface of fluid and gel phase 1,2-dimyristoyl(d54)-sn-glycero-3-phosphocholine (d-DMPC) lipid bilayers when the lipid bilayers are in contact with a peptide solution with a low concentration of 0.84 μM. However, at a medium peptide concentration of 10.80 μM, alamethicin inserts into the fluid phase lipid bilayer. Its orientation switches from a transmembrane to an in-plane (or lying down) orientation when the phase of the lipid bilayer changes from a fluid state to a gel state. At a high peptide concentration of 21.60 μM, alamethicin adopts a transmembrane orientation while associated with both fluid and gel phase lipid bilayers. We also studied the structural changes of the fluid and gel phase lipid bilayers upon their interactions with alamethicin molecules at different peptide concentrations.
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影响因子：
15
作者：
Fu, Li;Ma, Gang;Yan, Elsa C. Y.
通讯作者：
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作者：
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影响因子：
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作者：
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通讯作者：
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DOI：
10.1073/pnas.1108236108
发表时间：
2011-09-13
影响因子：
11.1
作者：
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通讯作者：
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影响因子：
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作者：
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