Protegrin interaction with lipid monolayers: grazing incidence X-ray diffraction and X-ray reflectivity study
Protegrin interaction with lipid monolayers: grazing incidence X-ray diffraction and X-ray reflectivity study
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DOI：
10.1039/b718295c
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发表时间：
2008-01-01
期刊：
影响因子：
3.4
通讯作者：
Gidalevitz, David
中科院分区：
文献类型：
--
作者：
Neville, Frances;Ishitsuka, Yuji;Gidalevitz, David
利用掠入射X射线衍射（GIXD）和镜面X射线反射率（XR）研究了抗菌肽保护素-1（PG-1）与磷脂单分子膜的相互作用。首次用X射线衍射研究了PG-1膜在空气-水界面上的结构。二棕榈酰磷脂酰胆碱（DPPC），二棕榈酰磷脂酰甘油（DPPG）和脂质A的单分子膜形成在空气-水界面，以模拟人红细胞，革兰氏阳性细菌细胞膜和革兰氏阴性细菌外膜，分别。在恒定面积条件下进行实验，其中在将肽插入单层中时压力发生变化。GIXD数据表明，在DPPG系统中，在20 mN m（-1）下观察到PG-1产生的最大单层破坏，因为在将PG-1引入系统后，布拉格峰完全消失。当两种膜保持在20 mN m（-1）的相同初始表面压力下时，PG-1显示出比DPPC系统更大的插入到脂质A系统中。DPPC和DPPG单分子膜体系在30 mN m（-1）时，插入程度减小. XR数据进一步揭示PG-1主要插入在脂质单层的头基区域。然而，只有阴离子脂质的XR数据表明，存在一个额外的吸附肽层下面的头部基团的单层。总体而言，数据显示肽-脂质相互作用和脂质单层破坏的程度不仅取决于单层的脂质组成，还取决于在将肽引入亚相之前单层中脂质的堆积密度。
Interactions of the antimicrobial peptide protegrin-1 (PG-1) with phospholipid monolayers have been investigated by using grazing incidence X-ray diffraction (GIXD) and specular X-ray reflectivity (XR). The structure of a PG-1 film at the air-aqueous interface was also investigated by XR for the first time. Dipalmitoyl phosphatidylcholine (DPPC), dipalmitoyl phosphatidylglycerol (DPPG) and lipid A monolayers were formed at the air-aqueous interface to mimic the surface of human erythrocytes, Gram-positive bacterial cell membranes and Gram-negative bacterial outer membranes, respectively. Experiments were carried out under constant area conditions where the pressure changes upon insertion of peptide into the monolayer. GIXD data suggest that the greatest monolayer disruption produced by PG-1 is seen with the DPPG system at 20 mN m(-1) since the Bragg peaks completely disappear after introduction of PG-1 to the system. PG-1 shows greater insertion into the lipid A system compared to the DPPC system when both films are held at the same initial surface pressure of 20 mN m(-1). The degree of insertion lessens at 30 mN m(-1) with both DPPC and DPPG monolayer systems. XR data further reveal that PG-1 inserts primarily in the head group region of lipid monolayers. However, only the XR data of the anionic lipids suggest the existence of an additional adsorbed peptide layer below the head group of the monolayer. Overall, the data show that the extent of peptide-lipid interaction and lipid monolayer disruption depends not only on the lipid composition of the monolayer, but the packing density of the lipids in the monolayer prior to the introduction of peptide to the subphase.