Quasi-elastic neutron scattering reveals the relationship between the dynamical behavior of phospholipid headgroups and hydration water.

IF 2.3 2区物理与天体物理 Q3 CHEMISTRY, PHYSICAL

Structural Dynamics-Us Pub Date : 2023-07-01 DOI:10.1063/4.0000184

Md Khalidur Rahman, Takeshi Yamada, Norifumi L Yamada, Mafumi Hishida, Yuji Higuchi, Hideki Seto

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引用次数: 1

Abstract

The dynamics of hydration water (HW) in 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine (DMPE) was investigated by means of quasi-elastic neutron scattering (QENS) and compared with those observed in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). The headgroup dynamics of DMPE was investigated using a mixture of tail-deuterated DMPE and D₂O, and the QENS profiles were interpreted as consisting of three modes. The fast mode comprised the rotation of hydrogen atoms in -NH₃⁺ and -CH₂- groups in the headgroup of DMPE, the medium-speed mode comprised fluctuations in the entire DMPE molecule, and the slow mode comprised fluctuations in the membrane. These interpretations were confirmed using molecular dynamics (MD) simulations. The HW dynamics analysis was performed on a tail-deuterated DMPE and H₂O mixture. The QENS profiles were analyzed in terms of three modes: (1) a slow mode, identified as loosely bound HW in the DMPC membrane; (2) a medium-speed mode similar to free HW in the DMPC membrane; and (3) a fast mode, identified as rotational motion. The relaxation time for the fast mode was approximately six times shorter than that of rotational water in DMPC, consistent with the results of terahertz time-domain spectroscopy. The activation energy of medium-speed HW in DMPE differed from that of free HW in DMPC, suggesting the presence of different hydration states or hydrogen-bonded networks around the phosphocholine and phosphoethanolamine headgroups.

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准弹性中子散射揭示了磷脂头基的动力学行为与水合水之间的关系。

采用准弹性中子散射(QENS)研究了1,2-二肉豆醇基-sn-甘油-3-磷酸乙醇胺(DMPE)中水化水(HW)的动力学，并与1,2-二肉豆醇基-sn-甘油-3-磷酸胆碱(DMPC)中的水化水动力学进行了比较。采用尾氘化DMPE和D2O的混合物研究了DMPE的头群动力学，并将QENS剖面解释为由三种模式组成。快速模式包括DMPE头基- nh3 +和- ch2 -基团中氢原子的旋转，中速模式包括整个DMPE分子的波动，慢速模式包括膜的波动。这些解释通过分子动力学(MD)模拟得到了证实。对尾氘化DMPE和H2O混合物进行了HW动力学分析。QENS谱分为三种模式:(1)慢模式，即DMPC膜中松散结合的HW;(2)类似于DMPC膜中游离HW的中速模式;(3)快速模式，确定为旋转运动。在DMPC中，快速模式的弛豫时间比旋转水的弛豫时间短约6倍，与太赫兹时域光谱结果一致。DMPE中速HW的活化能与DMPC中游离HW的活化能不同，表明在磷酸胆碱和磷酸乙醇胺头基周围存在不同的水合状态或氢键网络。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Structural Dynamics-Us CHEMISTRY, PHYSICALPHYSICS, ATOMIC, MOLECU-PHYSICS, ATOMIC, MOLECULAR & CHEMICAL

CiteScore

5.50

自引率

3.60%

发文量

审稿时长

16 weeks

期刊介绍： Structural Dynamics focuses on the recent developments in experimental and theoretical methods and techniques that allow a visualization of the electronic and geometric structural changes in real time of chemical, biological, and condensed-matter systems. The community of scientists and engineers working on structural dynamics in such diverse systems often use similar instrumentation and methods. The journal welcomes articles dealing with fundamental problems of electronic and structural dynamics that are tackled by new methods, such as: Time-resolved X-ray and electron diffraction and scattering, Coherent diffractive imaging, Time-resolved X-ray spectroscopies (absorption, emission, resonant inelastic scattering, etc.), Time-resolved electron energy loss spectroscopy (EELS) and electron microscopy, Time-resolved photoelectron spectroscopies (UPS, XPS, ARPES, etc.), Multidimensional spectroscopies in the infrared, the visible and the ultraviolet, Nonlinear spectroscopies in the VUV, the soft and the hard X-ray domains, Theory and computational methods and algorithms for the analysis and description of structuraldynamics and their associated experimental signals. These new methods are enabled by new instrumentation, such as: X-ray free electron lasers, which provide flux, coherence, and time resolution, New sources of ultrashort electron pulses, New sources of ultrashort vacuum ultraviolet (VUV) to hard X-ray pulses, such as high-harmonic generation (HHG) sources or plasma-based sources, New sources of ultrashort infrared and terahertz (THz) radiation, New detectors for X-rays and electrons, New sample handling and delivery schemes, New computational capabilities.

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