Site-Specific Peptide Probes Detect Buried Water in a Lipid Membrane
Site-Specific Peptide Probes Detect Buried Water in a Lipid Membrane
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DOI：
10.1016/j.bpj.2019.03.002
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发表时间：
2019-05-07
影响因子：
3.4
通讯作者：
Baiz, Carlos R.
中科院分区：
文献类型：
--
作者：
Flanagan, Jennifer C.;Baiz, Carlos R.
跨膜肽在膜的内部含有极性残基，其可改变静电环境并有利于膜核心的非极性环境中的水合。在这里，我们展示了一个通用的，非微扰的策略，探测水化的肽骨架在特定的深度内的双层结合使用特定位点的同位素标记，超快二维红外光谱，和光谱建模的基础上分子动力学模拟。我们的研究结果表明，两亲性的pH值低的插入肽支持一个高度异质性的环境，具有显着的非极性残基附近的带电残基的骨干水合。例如，位于疏水性主体中1 nm处的亮氨酸残基报告氢键群高达接近20%。这些发现表明，这些残基的极性性质可能有助于水分子进入膜的疏水核心的运输。
Transmembrane peptides contain polar residues in the interior of the membrane, which may alter the electrostatic environment and favor hydration in the otherwise nonpolar environment of the membrane core. Here, we demonstrate a general, nonperturbative strategy to probe hydration of the peptide backbone at specific depths within the bilayer using a combination of site-specific isotope labels, ultrafast two-dimensional infrared spectroscopy, and spectral modeling based on molecular dynamics simulations. Our results show that the amphiphilic pH-low insertion peptide supports a highly heterogeneous environment, with significant backbone hydration of nonpolar residues neighboring charged residues. For example, a leucine residue located as far as 1 nm into the hydrophobic bulk reports hydrogen-bonded populations as high as similar to 20%. These findings indicate that the polar nature of these residues may facilitate the transport of water molecules into the hydrophobic core of the membrane.