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Title: Direct comparison of elastic incoherent neutron scattering experiments with molecular dynamics simulations of DMPC phase transitions

Abstract

Neutron scattering techniques have been employed to investigate 1,2-dimyristoyl-sn-glycero-3- phosphocholine (DMPC) membranes in the form of multilamellar vesicles (MLVs) and deposited, stacked multilamellar-bilayers (MLBs), covering transitions from the gel to the liquid phase. Neutron diffraction was used to characterise the samples in terms of transition temperatures, whereas elastic incoherent neutron scattering (EINS) demonstrates that the dynamics on the sub-macromolecular length-scale and pico- to nano-second time-scale are correlated with the structural transitions through a discontinuity in the observed elastic intensities and the derived mean square displacements. Molecular dynamics simulations have been performed in parallel focussing on the length-, time- and temperature-scales of the neutron experiments. They correctly reproduce the structural features of the main gel-liquid phase transition. Particular emphasis is placed on the dynamical amplitudes derived from experiment and simulations. Two methods are used to analyse the experimental data and mean square displacements. They agree within a factor of 2 irrespective of the probed time-scale, i.e. the instrument utilized. Mean square displacements computed from simulations show a comparable level of agreement with the experimental values, albeit, the best match with the two methods varies for the two instruments. Consequently, experiments and simulations together give a consistent picture of the structural andmore » dynamical aspects of the main lipid transition and provide a basis for future, theoretical modelling of dynamics and phase behaviour in membranes. The need for more detailed analytical models is pointed out by the remaining variation of the dynamical amplitudes derived in two different ways from experiments on the one hand and simulations on the other.« less

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
Institut Laue-Langevin
OSTI Identifier:
1392488
DOE Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
European Physical Journal. E, Soft Matter
Additional Journal Information:
Journal Volume: 39; Journal Issue: 4; Journal ID: ISSN 1292-8941
Publisher:
EDP Sciences
Country of Publication:
United States
Language:
English

Citation Formats

Aoun, Bachir, Pellegrini, Eric, Trapp, Marcus, Natali, Francesca, Cantù, Laura, Brocca, Paola, Gerelli, Yuri, Demé, Bruno, Marek Koza, Michael, Johnson, Mark, and Peters, Judith. Direct comparison of elastic incoherent neutron scattering experiments with molecular dynamics simulations of DMPC phase transitions. United States: N. p., 2016. Web. doi:10.1140/epje/i2016-16048-y.
Aoun, Bachir, Pellegrini, Eric, Trapp, Marcus, Natali, Francesca, Cantù, Laura, Brocca, Paola, Gerelli, Yuri, Demé, Bruno, Marek Koza, Michael, Johnson, Mark, & Peters, Judith. Direct comparison of elastic incoherent neutron scattering experiments with molecular dynamics simulations of DMPC phase transitions. United States. doi:10.1140/epje/i2016-16048-y.
Aoun, Bachir, Pellegrini, Eric, Trapp, Marcus, Natali, Francesca, Cantù, Laura, Brocca, Paola, Gerelli, Yuri, Demé, Bruno, Marek Koza, Michael, Johnson, Mark, and Peters, Judith. Fri . "Direct comparison of elastic incoherent neutron scattering experiments with molecular dynamics simulations of DMPC phase transitions". United States. doi:10.1140/epje/i2016-16048-y.
@article{osti_1392488,
title = {Direct comparison of elastic incoherent neutron scattering experiments with molecular dynamics simulations of DMPC phase transitions},
author = {Aoun, Bachir and Pellegrini, Eric and Trapp, Marcus and Natali, Francesca and Cantù, Laura and Brocca, Paola and Gerelli, Yuri and Demé, Bruno and Marek Koza, Michael and Johnson, Mark and Peters, Judith},
abstractNote = {Neutron scattering techniques have been employed to investigate 1,2-dimyristoyl-sn-glycero-3- phosphocholine (DMPC) membranes in the form of multilamellar vesicles (MLVs) and deposited, stacked multilamellar-bilayers (MLBs), covering transitions from the gel to the liquid phase. Neutron diffraction was used to characterise the samples in terms of transition temperatures, whereas elastic incoherent neutron scattering (EINS) demonstrates that the dynamics on the sub-macromolecular length-scale and pico- to nano-second time-scale are correlated with the structural transitions through a discontinuity in the observed elastic intensities and the derived mean square displacements. Molecular dynamics simulations have been performed in parallel focussing on the length-, time- and temperature-scales of the neutron experiments. They correctly reproduce the structural features of the main gel-liquid phase transition. Particular emphasis is placed on the dynamical amplitudes derived from experiment and simulations. Two methods are used to analyse the experimental data and mean square displacements. They agree within a factor of 2 irrespective of the probed time-scale, i.e. the instrument utilized. Mean square displacements computed from simulations show a comparable level of agreement with the experimental values, albeit, the best match with the two methods varies for the two instruments. Consequently, experiments and simulations together give a consistent picture of the structural and dynamical aspects of the main lipid transition and provide a basis for future, theoretical modelling of dynamics and phase behaviour in membranes. The need for more detailed analytical models is pointed out by the remaining variation of the dynamical amplitudes derived in two different ways from experiments on the one hand and simulations on the other.},
doi = {10.1140/epje/i2016-16048-y},
journal = {European Physical Journal. E, Soft Matter},
issn = {1292-8941},
number = 4,
volume = 39,
place = {United States},
year = {2016},
month = {4}
}

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