Molecular interactions between magainin 2 and model membranes in situ.
Molecular interactions between magainin 2 and model membranes in situ.
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DOI：
10.1021/jp904154w
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发表时间：
2009-09-10
期刊：
影响因子：
--
通讯作者：
Chen Z
中科院分区：
文献类型：
--
作者：
Nguyen KT;Le Clair SV;Ye S;Chen Z
本文采用和频振动光谱法和衰减全反射-傅里叶变换红外光谱法（ATR-FTIR）研究了Magainin 2与模型细胞膜的分子相互作用。在研究中使用分别模拟细菌和哺乳动物细胞膜的对称的1-棕榈酰基-2-油酰基-sn-甘油-3-[磷酸-rac-（1-甘油）]（POPG）和1-棕榈酰基-2-油酰基-sn-甘油-3-磷酸胆碱（POPC）双层。通过SFG观察到，在约200 nM的低溶液浓度下，爪蟾抗菌肽2相对平行于POPG脂质双层表面取向。当将爪蟾抗菌肽2的浓度增加到800 nM时，SFG和ATR-FTIR结果均表明爪蟾抗菌肽2分子插入POPG双层中，并采用与POPG双层法线成约20度角的跨膜取向。对于POPC双层，即使在2.0 µM的高得多的肽浓度下，也没有检测到ATR-FTIR信号。对于POPC上的该浓度，SFG研究表明，爪蟾抗菌肽2分子采用几乎平行于双层表面的取向，与表面法线的取向角为75度。这表明SFG具有比ATR-FTIR好得多的检测限，因此可以应用于研究具有低得多的表面覆盖度的界面分子。这Magainin 2的取向研究和进一步调查的脂质双层SFG信号支持提出的环形孔模型的Magainin 2的抗微生物活性。
In this paper, we investigated the molecular interactions of Magainin 2 with model cell membranes using Sum Frequency Generation (SFG) vibrational spectroscopy and Attenuated Total Reflectance – Fourier Transform Infrared spectroscopy (ATR-FTIR). Symmetric 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-rac-(1-glycerol)] (POPG) and 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-Phosphocholine (POPC) bilayers, which model the bacterial and mammalian cell membranes respectively, were used in the studies. It was observed by SFG that Magainin 2 orients relatively parallel to the POPG lipid bilayer surface at low solution concentrations, around 200 nM. When increasing the Magainin 2 concentration to 800 nM, both SFG and ATR-FTIR results indicate that Magainin 2 molecules insert into the POPG bilayer and adopt a transmembrane orientation with an angle of about 20 degrees from the POPG bilayer normal. For the POPC bilayer, even at a much higher peptide concentration of 2.0 µM, no ATR-FTIR signal was detected. For this concentration on POPC, SFG studies indicated that Magainin 2 molecules adopt an orientation nearly parallel to the bilayer surface, with an orientation angle of 75 degrees from the surface normal. This shows that SFG has a much better detection limit than ATR-FTIR and can therefore be applied to study interfacial molecules with much lower surface coverage. This Magainin 2 orientation study and further investigation of the lipid bilayer SFG signals support the proposed toroidal pore model for the antimicrobial activity of Magainin 2.
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