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J Phys Chem B. 2017 Nov 2;121(43):10091-10104. doi: 10.1021/acs.jpcb.7b08967. Epub 2017 Oct 20.

Molecular Dynamics Simulations of Ceramide and Ceramide-Phosphatidylcholine Bilayers.

Author information

1
Department of Chemical and Biomolecular Engineering and ‡Biophysics Graduate Program, University of Maryland , College Park, Maryland 20742, United States.

Abstract

Recent studies in lipid raft formation and stratum corneum permeability have focused on the role of ceramides (CER). In this study, we use the all-atom CHARMM36 (C36) force field to simulate bilayers using N-palmitoylsphingosine (CER16) or α-hydroxy-N-stearoyl phytosphingosine (CER[AP]) in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), which serve as general membrane models. Conditions are replicated from experimental studies for comparison purposes, and concentration (XCER) is varied to probe the effect of CER on these systems. Comparisons with experiment based on deuterium order parameters and bilayer thickness demonstrate good agreement, thus supporting further use of the C36 force field. CER concentration is shown to have a profound effect on nearly all membrane properties including surface area per lipid, chain order and tilt, area compressibility moduli, bilayer thickness, hydrogen bonding, and lipid clustering. Hydrogen bonding in particular can significantly affect other membrane properties and can even encourage transition to a gel phase. Despite CER's tendency to condense the membrane, an expansion of CER lipids with increasing XCER is possible depending on how the balance between various hydrogen-bond pairs and lipid clustering is perturbed. Based on gel phase transitions, support is given for phytosphingosine's role as a hydrogen-bond bridge between sphingosine ordered domains in the stratum corneum.

PMID:
29017324
DOI:
10.1021/acs.jpcb.7b08967
[Indexed for MEDLINE]

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