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Molecular dynamics simulations of cardiolipin bilayers
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
Stockholm University, Faculty of Science, Department of Physical, Inorganic and Structural Chemistry.
2008 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 112, no 37, 11655-11663 p.Article in journal (Refereed) Published
Abstract [en]

Cardiolipin is a key lipid component in the inner mitochondrial membrane, where the lipid is involved in energy production, cristae structure, and mechanisms in the apoptotic pathway. In this article we used molecular dynamics computer simulations to investigate cardiolipin and its effect on the structure of lipid bilayers. Three cardiolipin/POPC bilayers with different lipid compositions were simulated: 100, 9.2, and 0% cardiolipin. We found strong association of sodium counterions to the carbonyl groups of both lipid types, leaving in the case of 9.2% cardiolipin virtually no ions in the aqueous compartment. Although binding occurred primarily at the carbonyl position, there was a preference to bind to the carbonyl groups of cardiolipin. Ion binding and the small headgroup of cardiolipin gave a strong ordering of the hydrocarbon chains. We found significant effects in the water dipole orientation and water dipole potential which can compensate for the electrostatic repulsion that otherwise should force charged lipids apart. Several parameters relevant for the molecular structure of cardiolipin were calculated and compared with results from analyses of coarse-grained simulations and available X-ray structural data.

Place, publisher, year, edition, pages
Whashington: AMER CHEMICAL SOC , 2008. Vol. 112, no 37, 11655-11663 p.
URN: urn:nbn:se:su:diva-15147DOI: 10.1021/jp803414gISI: 000259140600028OAI: diva2:181667
Available from: 2008-11-22 Created: 2008-11-22 Last updated: 2010-03-18Bibliographically approved
In thesis
1. Molecular Modeling of Cardiolipin
Open this publication in new window or tab >>Molecular Modeling of Cardiolipin
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Biological membranes are assembled from many different lipids. Our understanding of membrane function and morphology is dependent on linking the properties of the lipids to the properties of the membranes. In the inner mitochondrial membrane, one of the main lipids is cardiolipin, which is involved in the formation of high curvature tubular regions. In this thesis a series of molecular models of cardiolipin is presented, with the aim of providing a bottom-up understanding for its influence on model and biological membranes. The models allow detailed control over the headgroup charge and the chain volumes, which experimentally have shown to be important for the packing, mechanical, and electrostatic properties of membranes.To achieve these aims, three levels of detail were used: i) quantum chemical calculations for the cardiolipin headgroup, ii) atomistic united atom molecular dynamics simulations for cardiolipin and phosphatidylcholine lipid mixtures, and iii) coarse grained molecular dynamics simulations for larger lipid systems, including phase transitions between the micellar, lamellar, and inverse hexagonal phases, as well as mixtures of cardiolipin with zwitterionic lipids. These models are presented in the context of various experiments on cardiolipin systems done by others, and some basic theory of electrostatics and mechanics of membranes are discussed.The simple coarse grained model gave lipid phase preferences in agreement with experimental data. Relatively small amounts of partially neutralized cardiolipin molecules introduced mechanical instability in phosphatidylcholine bilayers, and showed some evidence of domain formation due to curvature frustration. The small effective headgroup volume of cardiolipin induced order in the hydrocarbon chains, partly due to strong sodium ion binding. Different types of intramolecular hydrogen bond networks in cardiolipin were described, and proton transfer between the phosphate groups within a cardiolipin molecule was estimated to have a 4-5 kcal/mol barrier. Such transfer might play a role in the surface conduction of protons at the inner mitochondrial membrane.

Place, publisher, year, edition, pages
Stockholm: Department of Materials and Environmental Chemistry (MMK), Stockholm University, 2010. 97 p.
National Category
Physical Chemistry
Research subject
Physical Chemistry
urn:nbn:se:su:diva-37613 (URN)978-91-7447-024-6 (ISBN)
Public defence
2010-04-16, Magnelisalen, Kemiska övningslaboratoriet, Svante Arrhenius väg 16 B, Stockholm, 13:00 (English)
At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Submitted.Available from: 2010-03-25 Created: 2010-03-16 Last updated: 2010-03-17Bibliographically approved

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Maliniak, ArnoldDahlberg, Martin
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