Structure, orientation and affinity for interfaces and lipids of ideally amphipathic lytic LiKj(i=2j) peptides
Structure, orientation and affinity for interfaces and lipids of ideally amphipathic lytic LiKj(i=2j) peptides
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DOI：
10.1016/s0005-2736(98)00220-x
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发表时间：
1999-01-12
影响因子：
3.4
通讯作者：
Dufourcq, J
中科院分区：
文献类型：
--
作者：
Castano, S;Desbat, B;Dufourcq, J
本文采用单分子膜技术结合偏振调制红外光谱技术（PMIRRAS），对两亲性多肽LiKj（i = 2 j）（LKn，n=i+j）的溶解行为进行了原位研究。相对于肽长度，二级结构发生变化。长度超过12个残基的肽在界面处折叠成α-螺旋，正如其设计所预期的那样，而足够短的肽，从9个到5个残基，形成分子间反平行β-折叠。在酰胺I和II区域的实验和计算的PMIRRAS光谱的分析表明，肽是平面取向的接口。无论界面、空气/水或DMPC单层的性质如何，以及侧向压力如何，结构和取向都得以保留。肽分配常数，K-aff（Pi），估计从DMPC单层的同量异位素表面增加。当Pi从30 mN/m降至8 mN/m时，它们强烈增加，并且它们随肽长度而变化，最佳为12个残基。这种非单调的依赖性与在双层中获得的数据相吻合，并且遵循肽的溶血活性。脂质扰动由于肽插入基本上检测到的PO 4-和CO带指示脂质头基团的紊乱。由这些肽诱导的膜上的裂解被认为是首先由它们的平坦不对称插入引起的。(C)1999 Elsevier Science B. V.保留所有权利。
The behavior of lytic ideally amphipathic peptides of generic composition LiKj(i = 2j) and named LKn, n=i+j, is investigated in situ by the monolayer technique combined with the recently developed polarization modulation IR spectroscopy (PMIRRAS). A change in the secondary structure occurs versus peptide length. Peptides longer than 12 residues fold into alpha-helices at interfaces as expected from their design, while enough shorter peptides, from 9 down to 5 residues, form intermolecular antiparallel beta-sheets. Analysis of experimental and calculated PMIRRAS spectra in the amide I and II regions show that peptides are flat oriented at the interfaces. Structures and orientation are preserved whatever the nature of the interface, air/water or DMPC monolayer, and the lateral pressure. Peptide partition constants, K-aff(Pi), are estimated from isobar surface increases of DMPC monolayers. They strongly increase when Pi decreases from 30 mN/m to 8 mN/m and they vary with peptide length with an optimum for 12 residues. This non-monotonous dependence fits with data obtained in bilayers and follows the hemolytic activity of the peptides. Lipid perturbations due to peptide insertion essentially detected on the PO4- and CO bands indicate disorder of the lipid head groups. Lysis induced on membranes by such peptides is proposed to first result from their flat asymmetric insertion. (C) 1999 Elsevier Science B.V. All rights reserved.