Phase Behavior of a Phospholipid/Fatty Acid/Water Mixture Studied in Atomic Detail

Molecular dynamics simulations have been used to study the phase behavior of a dipalmitoylphosphatidylcholine (DPPC)/palmitic acid (PA)/water 1:2:20 mixture in atomic detail. Starting from a random solution of DPPC and PA in water, the system adopts either a gel phase at temperatures below ∼330 K or...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2006-02, Vol.128 (6), p.2030-2034
Main Authors: Knecht, Volker, Mark, Alan E, Marrink, Siewert-Jan
Format: Article
Language:English
Subjects:
1,2-Dipalmitoylphosphatidylcholine - chemistry
Biological and medical sciences
Computer Simulation
Disperse state. Micelles
Fundamental and applied biological sciences. Psychology
Membrane Fusion
Models, Molecular
Molecular biophysics
Palmitic Acid - chemistry
Physico-chemical properties of biomolecules
Water - chemistry
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Summary:Molecular dynamics simulations have been used to study the phase behavior of a dipalmitoylphosphatidylcholine (DPPC)/palmitic acid (PA)/water 1:2:20 mixture in atomic detail. Starting from a random solution of DPPC and PA in water, the system adopts either a gel phase at temperatures below ∼330 K or an inverted hexagonal phase above ∼330 K in good agreement with experiment. It has also been possible to observe the direct transformation from a gel to an inverted hexagonal phase at elevated temperature (∼390 K). During this transformation, a metastable fluid lamellar intermediate is observed. Interlamellar connections or stalks form spontaneously on a nanosecond time scale and subsequently elongate, leading to the formation of an inverted hexagonal phase. This work opens the possibility of studying in detail how the formation of nonlamellar phases is affected by lipid composition and (fusion) peptides and, thus, is an important step toward understanding related biological processes, such as membrane fusion.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja056619o