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20–23 Mar 2023
Campus Garching
Europe/Berlin timezone

Hydration water dynamics between DMPE (1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine) phospholipid bilayers by quasi-elastic neutron scattering

22 Mar 2023, 17:00
20m
MW 0 001 - Lecture hall (Fakultät für Maschinenwesen)

MW 0 001 - Lecture hall

Fakultät für Maschinenwesen

666
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Speaker

Mr Md. Khalidur Rahman (Department of Materials Structure Science, KEK, The Graduate University for Advanced Studies (SOKENDAI))

Description

Terahertz time domain spectroscopy (THz-TDS) revealed that fast (rotational) water dynamics depend on phospholipid headgroup structure by comparing PC and PE [1], but the comparison between them for the loosely and tightly bound (translational) hydration water (HW) observed for DMPC by quasi-elastic neutron scattering (QENS) [2], is still not revealed. We have done QENS experiments on the d54-DMPE+10D2O, to observe DMPE headgroup modes. After separating the headgroup modes, we analyzed the QENS profiles of HW from the d54-DMPE+10H2O by the sum of three Lorentz functions corresponding to slow, middle speed, and fast modes. The relaxation time of the fast mode is approximately six times faster than that in DMPC estimated by THz-TDS [3]. The diffusion coefficient of the middle speed mode was the same order of magnitude as the free water, the slow mode was approximately the same as that of the loosely bound water observed in DMPC [2], while the tightly bound water was not identified because it may be embedded in the headgroup dynamics. We also found that activation energy estimated from the temperature dependence of the mean residence time of the free water in the vicinity of DMPE is significantly lower than that of DMPC [2]. We will discuss the headgroup dynamics with Molecular Dynamics simulation results.
References: [1] Hishida et al., J. Phys. Soc. Jpn. 2014, 83, 044801. [2] Yamada et al., J. Phys. Chem. B 2017, 121, 8322. [3] Choi et al., J. Chem. Phys. 2012, 137, 175101.

Primary author

Mr Md. Khalidur Rahman (Department of Materials Structure Science, KEK, The Graduate University for Advanced Studies (SOKENDAI))

Co-authors

Dr Takeshi Yamada (Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS)) Dr Norifumi L. Yamada (Department of Materials Structure Science, KEK, The Graduate University for Advanced Studies (SOKENDAI)) Dr Mafumi Hishida (Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba) Dr Yuji Higuchi (Research Institute for Information Technology, Kyushu University) Prof. Hideki Seto (Department of Materials Structure Science, KEK, The Graduate University for Advanced Studies (SOKENDAI))

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