Interdisciplinary Nanoscience Center (iNANO), Department of Molecular Biology, University of Aarhus, Gustav Wieds Vej 10C, DK - 8000 Aarhus C, Denmark.
J Colloid Interface Sci. 2010 May 15;345(2):248-56. doi: 10.1016/j.jcis.2010.01.065. Epub 2010 Jan 28.
We have studied the impact of an 18-residue cationic antimicrobial peptide Novicidin (Nc) on the structure and integrity of partially anionic lipid membranes using oriented circular dichroism (OCD), quartz crystal microbalance with dissipation (QCM-D), dual polarization interferometry (DPI), calcein dye leakage and fluorescence spectroscopy. OCD consistently showed that Nc is bound in an α-helical, surface bound state over a range of peptide to lipid (P/L) ratios up to ~1:15. Realignment of Nc at higher P/L ratios correlates to loss of membrane integrity as shown by Laurdan fluorescence spectroscopy and by loss of lipid alignment in DPI analysis. Laurdan generalized polarity shows a decrease in water accessibility or mobility in the hydrophobic/hydrophilic interface of the lipid membrane, consistent with rearrangement of lipid packing. QCM-D studies on the interaction of Nc with lipid membranes emphasize the importance of including the dissipation factor in data analysis, revealing formation of a highly hydrated film after exposure to ≥3 μM Nc. Our findings suggest a carpet mechanism of membrane disruption in which peptide binding first induces leakage at a critical surface concentration, probably through formation of transient pores or transient disruption of the membrane integrity, followed by more extensive membrane disintegration at higher P/L ratios.
我们使用定向圆二色性（OCD）、石英晶体微天平耗散（QCM-D）、双偏振干涉测量（DPI）、钙黄绿素染料渗漏和荧光光谱法研究了 18 个残基阳离子抗菌肽 Novicidin（Nc）对部分阴离子脂质膜结构和完整性的影响。OCD 一致表明，在高达 ~1:15 的肽脂（P/L）比范围内，Nc 以α-螺旋、表面结合的状态结合。在更高的 P/L 比下，Nc 的重新排列与膜完整性的丧失相关，如 Laurdan 荧光光谱法和 DPI 分析中脂质排列的丧失所示。Laurdan 普遍极性显示出疏水区/亲水区脂质膜界面处水的可及性或流动性降低，与脂质堆积的重新排列一致。Nc 与脂质膜相互作用的 QCM-D 研究强调了在数据分析中包括耗散因子的重要性，揭示了在暴露于≥3 μM Nc 后形成高度水合的膜。我们的研究结果表明，一种膜破坏的地毯机制，其中肽结合首先在临界表面浓度下诱导泄漏，可能是通过形成瞬时孔或暂时破坏膜完整性，然后在更高的 P/L 比下更广泛地破坏膜。
