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模型抗菌肽与单层磷脂囊泡相互作用时的缓慢插入动力学。

Slow insertion kinetics during interaction of a model antimicrobial peptide with unilamellar phospholipid vesicles.

机构信息

School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia.

出版信息

Langmuir. 2012 Jan 31;28(4):2217-24. doi: 10.1021/la203770j. Epub 2011 Dec 22.

Abstract

The mechanism of interaction between a model antimicrobial peptide and phospholipid unilamellar vesicle membranes was studied using fluorescence spectroscopy, fluorescence lifetime measurements, and light scattering. The peptide, a mellitin mutant, was labeled at position K14 with the polarity-sensitive probe AlexaFluor 430. The kinetics of the interaction of this derivative with various concentrations of 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) vesicles was examined. Our work unveiled two novel aspects of peptide-lipid interactions. First, the AB plot or phasor analysis of the fluorescence lifetime studies revealed at least three different peptide states, the population of which depended on the lipid to peptide (L:P) concentration ratio. Second, complex fluorescence kinetics were observed over extended time-scales from 30 s to 2 h. The extended kinetics was only observed at particular lipid concentrations (L:P ratios 20:1 and 10:1) and not at others (30, 40, 50 and 100:1 L:P ratio). Analysis of the complex kinetics revealed several intermediates. We assign these to distinct states of the peptide formed during helix insertion into the vesicle membrane that are intermediate to lytic pore formation.

摘要

采用荧光光谱法、荧光寿命测量法和光散射法研究了模型抗菌肽与磷脂单层囊泡膜之间的相互作用机制。该肽是一种蜂毒素突变体,在位置 K14 用极性敏感探针 AlexaFluor 430 进行了标记。研究了该衍生物与不同浓度的 1,2-二棕榈酰基-sn-甘油-3-磷酸胆碱(DPPC)囊泡相互作用的动力学。我们的工作揭示了肽-脂相互作用的两个新方面。首先,荧光寿命研究的 AB 图或相分析揭示了至少三种不同的肽态,其种群取决于脂质与肽的浓度比(L:P)。其次,在从 30 秒到 2 小时的扩展时间范围内观察到复杂的荧光动力学。这种扩展动力学仅在特定的脂质浓度(L:P 比为 20:1 和 10:1)下观察到,而在其他浓度(30、40、50 和 100:1 L:P 比)下则没有观察到。对复杂动力学的分析揭示了几个中间体。我们将这些分配给肽在插入囊泡膜期间形成的不同状态,这些状态介于溶孔形成之间。

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