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Structural transitions in ceramide cubic phases during formation of the human skin barrier
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Biological Physics.ORCID iD: 0000-0002-4591-9809
KTH, School of Engineering Sciences (SCI), Theoretical Physics, Theoretical Biological Physics.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

The stratum corneum is the outer-most layer of the human skin, and constitutes the primary barrier to penetration of external substances. The barrier function of the stratum corneum is primarily located to its extracellular space, which consists of long-chain ceramides, free fatty acids and cholesterol organised into a stacked lamellar bilayer structure. Recent experimental studies have shown that these lamellar structures are formed through a structural reorganization of glycosylceramide-based bilayers, folded in three dimensions with a cubic-like symmetry. Here we present coarse-grained molecular dynamics simulations of human ceramide- and glycosylceramide bilayer structures with gyroid cubic symmetry. The bilayer structures with glycosylceramides are able to maintain the cubic symmetry, while the bilayer structures with ceramides collapse into a stacked lamellar bilayer structure as the water content is reduced.

National Category
Biophysics
Identifiers
URN: urn:nbn:se:kth:diva-183361OAI: oai:DiVA.org:kth-183361DiVA: diva2:910000
Note

QS 2016

Available from: 2016-03-08 Created: 2016-03-08 Last updated: 2016-03-08Bibliographically approved
In thesis
1. Computational modeling of biological barriers
Open this publication in new window or tab >>Computational modeling of biological barriers
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

One of the most important aspects for all life on this planet is the act to keep their biological processes in a state where they do not reach equilibrium. One part in the upholding of this imbalanced state is the barrier between the cells and their surroundings, created by the cell membrane. Additionally, terrestrial animal life often requires a barrier that protects the organism's body from external hazards and water loss. As an alternative to experiments, the investigation of the processes occurring at these barriers can be performed by using molecular dynamics simulations. Through this method we can obtain an atomistic description of the dynamics associated with events that are not accessible to experimental setups.

 In this thesis the first paper presents an improved particle-mesh Ewald method for the calculation of long-range Lennard-Jones interactions in molecular dynamics simulations, which solves the historical performance problem of the method. The second paper demonstrate an improved implementation, with a higher accuracy, that only incurs a performance loss of roughly 15% compared to conventional simulations using the Gromacs simulation package. Furthermore, the third paper presents a study of cholesterol's effect on the permeation of six different solutes across a variety of lipid bilayers. A laterally inhomogeneous permeability in cholesterol-containing membranes is proposed as an explanation for the large differences between experimental permeabilities and calculated partition coefficients in simulations. The fourth paper contains a coarse-grained simulation study of a proposed structural transformation in ceramide bilayer structures, during the formation of the stratum corneum. The simulations show that glycosylceramides are able to stabilize a three-dimensionally folded bilayer structure, while simulations with ceramides collapse into a lamellar bilayer structure.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. xii, 49 p.
Series
TRITA-FYS, ISSN 0280-316X ; 2016:10
Keyword
Molecular dynamics, cholesterol, lipid bilayer, permeability, long-range interactions, Lennard-Jones, dispersion, particle-mesh Ewald, stratum corneum, skin formation
National Category
Biophysics
Research subject
Biological Physics
Identifiers
urn:nbn:se:kth:diva-183362 (URN)978-91-7595-884-2 (ISBN)
Public defence
2016-04-15, sal F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
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Supervisors
Note

QC 20160308

Available from: 2016-03-08 Created: 2016-03-08 Last updated: 2016-03-09Bibliographically approved

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