Investigating the Secondary Structure of Membrane Peptides Utilizing Multiple 2 H-Labeled Hydrophobic Amino Acids via Electron Spin Echo Envelope Modulation (ESEEM) Spectroscopy
Investigating the Secondary Structure of Membrane Peptides Utilizing Multiple 2 H-Labeled Hydrophobic Amino Acids via Electron Spin Echo Envelope Modulation (ESEEM) Spectroscopy
复制标题
利用多个 2 H 标记的疏水性氨基酸通过电子自旋回波包络调制 (ESEEM) 光谱研究膜肽的二级结构
DOI：
10.1021/acs.jpcb.7b11890
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Lorigan, Gary A.
中科院分区：
文献类型：
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作者：
Liu, Lishan;Sahu, Indra D.;Bottorf, Lauren;McCarrick, Robert M.;Lorigan, Gary A.
电子自旋回波包络调制（ESEEM）方法被用来探测膜蛋白和肽的局部二级结构。该ESEEM方法检测氨基酸（Leu或瓦尔）侧链上的2 H-标记核与策略性放置的氮氧自旋标记之间的偶极偶联，其接近度高达8 μ m。不同样品的ESEEM谱图与不同二级结构的周期性结构特征直接相关。由于这种模式可能受到实验中使用的2 H标记氨基酸的侧链长度和柔性的影响，因此利用这种ESEEM方法检查几种不同的疏水氨基酸（d3 Ala，d8 Val，d8 Phe）是很重要的。在这项工作中，收集了一系列的ESEEM数据上的AChR M2δ膜肽，建立一个参考，为未来的应用这种方法的各种生物系统。结果表明，尽管相对强度和信噪比水平不同，但所有氨基酸对α-螺旋结构的ESEEM调制模式相似。因此，所有市售的2 H标记的疏水性氨基酸都可以用作探针，用于进一步应用这种ESEEM方法。此外，ESEEM信号强度随着侧链长度变长或刚性变小而增加。此外，当与相应的i ± 3样品相比时，较长侧链氨基酸在i ± 4样品中具有更大的以2 H拉莫尔频率为中心的2 H ESEEM FT峰。对于较短侧链氨基酸，2 H ESEEM FT峰强度比在1 ± 4和± 3之间不明确。
An electron spin echo envelope modulation (ESEEM) approach was used to probe local secondary structures of membrane proteins and peptides. This ESEEM method detects dipolar couplings between2H-labeled nuclei on the side chains of an amino acid (Leu or Val) and a strategically placed nitroxide spin-label in the proximity up to 8 Å. ESEEM spectra patterns for different samples correlate directly to the periodic structural feature of different secondary structures. Since this pattern can be affected by the side chain length and flexibility of the2H-labeled amino acid used in the experiment, it is important to examine several different hydrophobic amino acids (d3Ala, d8Val, d8Phe) utilizing this ESEEM approach. In this work, a series of ESEEM data were collected on the AChR M2δ membrane peptide to build a reference for the future application of this approach for various biological systems. The results indicate that, despite the relative intensity and signal-to-noise level, all amino acids share a similar ESEEM modulation pattern for α-helical structures. Thus, all commercially available2H-labeled hydrophobic amino acids can be utilized as probes for the further application of this ESEEM approach. Also, the ESEEM signal intensities increase as the side chain length gets longer or less rigid. In addition, longer side chain amino acids had a larger2H ESEEM FT peak centered at the2H Larmor frequency for thei± 4 sample when compared to the correspondingi± 3 sample. For shorter side chain amino acids, the2H ESEEM FT peak intensity ratio betweeni± 4 andi± 3 was not well-defined.