The molecular structure of a phosphatidylserine bilayer determined by scattering and molecular dynamics simulations

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DOIResolve DOI: http://doi.org/10.1039/c4sm00066h
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TypeArticle
Journal titleSoft Matter
ISSN1744-6848
Volume10
Issue21
Pages37163725; # of pages: 10
SubjectAmino acids; Atoms; Cell death; Lipid bilayers; Molecular dynamics; Molecular structure; Scattering; Area compressibility; Atomic-scale interaction; Molecular dynamics simulations; Phosphatidylcholine; Phosphatidylserine; Physiological functions; Preferential interaction; United-atom models; Computer simulation
AbstractPhosphatidylserine (PS) lipids play essential roles in biological processes, including enzyme activation and apoptosis. We report on the molecular structure and atomic scale interactions of a fluid bilayer composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylserine (POPS). A scattering density profile model, aided by molecular dynamics (MD) simulations, was developed to jointly refine different contrast small-angle neutron and X-ray scattering data, which yielded a lipid area of 62.7 Å2 at 25 °C. MD simulations with POPS lipid area constrained at different values were also performed using all-atom and aliphatic united-atom models. The optimal simulated bilayer was obtained using a model-free comparison approach. Examination of the simulated bilayer, which agrees best with the experimental scattering data, reveals a preferential interaction between Na+ ions and the terminal serine and phosphate moieties. Long-range inter-lipid interactions were identified, primarily between the positively charged ammonium, and the negatively charged carboxylic and phosphate oxygens. The area compressibility modulus KA of the POPS bilayer was derived by quantifying lipid area as a function of surface tension from area-constrained MD simulations. It was found that POPS bilayers possess a much larger K A than that of neutral phosphatidylcholine lipid bilayers. We propose that the unique molecular features of POPS bilayers may play an important role in certain physiological functions. This journal is © the Partner Organisations 2014.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); NRC Canadian Neutron Beam Centre (CNBC-CCFN)
Peer reviewedYes
NPARC number21272116
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Record identifier5d3f0a1f-0349-4e7a-bddd-dbab8a707959
Record created2014-07-23
Record modified2016-05-09
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