The mechanism of vesicle fusion as revealed by molecular dynamics simulations

Journal of the American Chemical Society

Volumn 125, Issue 37, 2003, Pages 11144-11145

  Marrink, Siewert J ^a   Mark, Alan E ^a  

^a UNIVERSITY OF GRONINGEN   (Netherlands)

Author keywords

[No Author keywords available]

Indexed keywords

ARTICLE; LIPID COMPOSITION; LIPID VESICLE; MEMBRANE FUSION; MOLECULAR DYNAMICS; MOLECULAR INTERACTION; MOLECULAR STABILITY; SIMULATION;

CYTOPLASMIC VESICLES; MEMBRANE FUSION; MEMBRANES, ARTIFICIAL; PHOSPHOLIPIDS; SOLVENTS;

EID: 0042193019     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja036138+     Document Type: Article

References (19)

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9. The pairwise interactions between the CG atoms are modeled by Lennard-Jones (LJ) interactions. They range from weak (hydrophobic interactions) to strong (polar interactions) with three levels in between. A screened Coulombic interaction is used for the electrostatic interaction between the zwitterionic headgroups. Both LJ and Coulombic interactions are only short-ranged, using a shift-based cutoff of 1.2 nm. Soft springs between bonded pairs keep the molecule together. Angle potentials provide the adequate stiffness for the lipid tails.
10. Marrink, S. J.; Mark, A. E. J. Am. Chem. Soc. 2003. Manuscript submitted
11. The systems are simulated using the GROMACS software (Lindahl, E.; Hess, B.; Spoel, D. J. Mol. Mod. 2001, 7, 306) with a time step of t = 200 fs. The time scale in the CG model is scaled to reproduce the diffusion rate of lipids and water. Constant temperature (T = 300) and isotropic pressure (P = 1 atm) conditions were applied which keep the lipids in the biologically relevant fluid state.
12. Experimentally, smallest vesicles obtained are ∼20 nm diameter. Cornell, B. A.; Fletcher, G. C.; Middlehurst, J.; Separovic, F. Biochim. Biophys. Acta 1982, 690, 15.
13. The resulting vesicle slowly relaxes (∼100 ns) into a tubular structure, a process limited by the rate of adsorption of external water. Lateral diffusion of the lipids causes mixing of the lipids in both monolayers, but not between the inner and outer monolayers. Lipid flipflops are absent on the time scale of the simulations, preventing the tubular vesicle from becoming spherical.
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