Orientation of Fluorescent Lipid Analogue BODIPY-PC to Probe Lipid Membrane Properties: Insights from Molecular Dynamics Simulations
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- 作者：Kevin C. Song ; Philip W. Livanec ; Jeffery B. Klauda ; Krzysztof Kuczera ; Robert C. Dunn ; Wonpil Im
- 刊名：Journal of Physical Chemistry B
- 出版年：2011
- 出版时间：May 19, 2011
- 年：2011
- 卷：115
- 期：19
- 页码：6157-6165
- 全文大小：1221K
- 年卷期：v.115,no.19(May 19, 2011)
- ISSN：1520-5207
文摘
Single-molecule fluorescence measurements have been used to characterize membrane properties, and recently showed a linear evolution of the fluorescent lipid analogue BODIPY-PC toward small tilt angles in Langmuir鈥揃lodgett monolayers as the lateral surface pressure is increased. In this work, we have performed comparative molecular dynamics (MD) simulations of BODIPY-PC in DPPC (dipalmitoylphosphatidylcholine) monolayers and bilayers at three surface pressures (3, 10, and 40 mN/m) to explore (1) the microscopic correspondence between monolayer and bilayer structures, (2) the fluorophore鈥檚 position within the membrane, and (3) the microscopic driving forces governing the fluorophore鈥檚 tilting. The MD simulations reveal very close agreement between the monolayer and bilayer systems in terms of the fluorophore鈥檚 orientation and lipid chain order, suggesting that monolayer experiments can be used to approximate bilayer systems. The simulations capture the trend of reduced tilt angle of the fluorophore with increasing surface pressure, as seen in the experimental results, and provide detailed insights into fluorophore location and orientation, not obtainable in the experiments. The simulations also reveal that the enthalpic contribution is dominant at 40 mN/m, resulting in smaller tilt angles of the fluorophore, and the entropy contribution is dominant at lower pressures, resulting in larger tilt angles.