State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, National Demonstration Center for Experimental Biomedical Engineering Education, Southeast University , Nanjing 210096, China.
Langmuir. 2018 Jan 9;34(1):512-520. doi: 10.1021/acs.langmuir.7b03411. Epub 2017 Dec 20.
Sum frequency generation (SFG) vibrational spectroscopy was used to study surface immobilization effects on the interactions between antimicrobial peptide cecropin P1 (CP1) and model cell membranes. While free CP1 in solution interacted with a model cell membrane composed of a phosphatidylglycerol (PG) bilayer, electrostatic interaction led to the attachment of CP1 molecules onto the PG surface and the hydrophobic domain in the lipid bilayer enabled the peptides to insert into the bilayer and form α-helices from random coil structures. While CP1 molecules immobilized on a self-assembled monolayer interacted with PG lipid vesicles, the intensity of the SFG peak for the peptide α-helix decreased as the PG vesicle concentration increased. It was believed that when surface-immobilized CP1 molecules interacted with lipid vesicles, they lay down on the surface or became random coils. When the immobilized CP1 interacted with a PG lipid monolayer on water, the strong interaction led to the lying-down orientation of all of the surface-immobilized peptides as well. Differently, no significant interactions between surface-immobilized CP1 with the mammalian cell membrane model 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayer were observed. Our results suggest that, instead of membrane insertion, the electrostatic interactions between the surface cationic charges of CP1 and anionic bacterial membranes may play an important role in the antimicrobial activity of the surface-immobilized CP1 peptide.
和频产生（SFG）振动光谱用于研究表面固定化对抗菌肽 Cecropin P1（CP1）与模型细胞膜之间相互作用的影响。当游离的 CP1 在溶液中与由磷脂酰甘油（PG）双层组成的模型细胞膜相互作用时，静电相互作用导致 CP1 分子附着在 PG 表面上，并且脂质双层中的疏水区使肽插入双层并从无规卷曲结构形成α-螺旋。当固定在自组装单层上的 CP1 分子与 PG 脂质囊泡相互作用时，随着 PG 囊泡浓度的增加，肽α-螺旋的 SFG 峰强度降低。据信，当表面固定的 CP1 分子与脂质囊泡相互作用时，它们要么躺在表面上，要么变成无规卷曲。当固定在 CP1 与水相上的 PG 脂质单层相互作用时，强烈的相互作用导致所有表面固定的肽都处于躺下的取向。不同的是，在表面固定的 CP1 与哺乳动物细胞膜模型 1-棕榈酰基-2-油酰基-sn-甘油-3-磷酸胆碱双层之间没有观察到明显的相互作用。我们的结果表明，在表面固定的 CP1 肽的抗菌活性中，CP1 的表面阳离子电荷与阴离子细菌膜之间的静电相互作用可能比膜插入更重要。
