Binding of the antibacterial peptide magainin 2 amide to small and large unilamellar vesicles
Binding of the antibacterial peptide magainin 2 amide to small and large unilamellar vesicles
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DOI：
10.1016/s0301-4622(00)00120-4
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发表时间：
2000-07-15
影响因子：
3.8
通讯作者：
Seelig, J
中科院分区：
文献类型：
--
作者：
Wieprecht, T;Apostolov, O;Seelig, J
用等温滴定量热法（ITC）和圆二色谱法（CD）研究了抗菌肽爪蟾抗菌肽2酰胺（M2 a）与带负电荷的小（SUV）和大（LUV）单层囊泡结合的热力学。结合等温线以及肽透化膜的能力被发现是定性和定量的两个模型膜相似。结合等温线可以用表面分配平衡来描述，其中用Gouy-Chapman理论计算结合平面正上方的肽的表面浓度。结合的标准自由能为Δ G（0），接近-22 kJ/mol，并且对于LUV和SW几乎相同。然而，LUV的标准结合焓和熵（Δ H-0 = -15.1 kJ/mol，Δ S-0 = 24.7 J/molK）明显高于SUV（Δ H-0 = -38.5 kJ/mol，Δ S-0 = -55.3 J/molK）。这种熵-熵补偿机制可以用脂质堆积的差异来解释。脂质分子之间的内聚力在良好包装的LUV中更大，并且与肽掺入到更无序的SUV中相比，M2 a的掺入导致内聚力的更强破坏和脂质柔性的更大增加。在45 ° C下，如从ITC曲线的模拟所判断的，肽容易从外单层移位到内单层。(C)2000 Elsevier Science B. V.保留所有权利。
The thermodynamics of binding of the antibacterial peptide magainin 2 amide (M2a) to negatively charged small (SUVs) and large (LUVs) unilamellar vesicles has been studied with isothermal titration calorimetry (ITC) and CD spectroscopy at 45 degrees C. The binding isotherms as well as the ability of the peptide to permeabilize membranes were found to be qualitatively and quantitatively similar for both model membranes. The binding isotherms could be described with a surface partition equilibrium where the surface concentration of the peptide immediately above the plane of binding was calculated with the Gouy-Chapman theory. The standard free energy of binding was Delta G(0) approximate to -22 kJ/mol and was almost identical for LUVs and SWs. However, the standard enthalpy and entropy of binding were distinctly higher for LUVs (Delta H-0 = -15.1 kJ/mol, Delta S-0 = 24.7 J/molK) than for SUVs (Delta H-0 = -38.5 kJ/mol, Delta S-0 = -55.3 J/molK). This enthalpy-entropy compensation mechanism is explained by differences in the lipid packing. The cohesive forces between lipid molecules are larger in well-packed LUVs and incorporation of M2a leads to a stronger disruption of cohesive forces and to a larger increase in the lipid flexibility than peptide incorporation into the more disordered SUVs. At 45 degrees C the peptide easily translocates from the outer to the inner monolayer as judged from the simulation of the ITC curves. (C) 2000 Elsevier Science B.V. All rights reserved.