help button home button Biophys. J.
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Michonova-Alexova, E. I.
Right arrow Articles by Sugár, I. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Michonova-Alexova, E. I.
Right arrow Articles by Sugár, I. P.

Biophys J, October 2002, p. 1820-1833, Vol. 83, No. 4

Component and State Separation in DMPC/DSPC Lipid Bilayers: A Monte Carlo Simulation Study

Ekaterina I. Michonova-Alexova and István P. Sugár

Departments of Biomathematical Sciences and Physiology/Biophysics, Mount Sinai School of Medicine at New York University, New York, New York 10029 USA

In this paper a two-state, two-component, Ising-type model is used to simulate the lateral distribution of the components and gel/fluid state acyl chains in dimyristoylphosphatidylcholine/distearoylphosphatidylcholine (DMPC/DSPC) lipid bilayers. The same model has been successful in calculating the excess heat capacity curves, the fluorescence recovery after photobleaching (FRAP) threshold temperatures, the most frequent center-to-center distances between DSPC clusters, and the fractal dimensions of gel clusters (Sugar, I. P., T. E. Thompson, and R. L. Biltonen, 1999. Biophys. J. 76:2099-2110). Depending on the temperature and mole fraction the population of the cluster size is either homogeneous or inhomogeneous. In the inhomogeneous population the size of the largest cluster scales with the size of the system, while the rest of the clusters remain small with increasing system size. In a homogeneous population, however, every cluster remains small with increasing system size. For both compositional and fluid/gel state clusters, threshold temperatures---the so-called percolation threshold temperatures---are determined where change in the type of the population takes place. At a given mole fraction, the number of percolation threshold temperatures can be 0, 1, 2, or 3. By plotting these percolation threshold temperatures on the temperature/mole fraction plane, the diagrams of component and state separation of DMPC/DSPC bilayers are constructed. In agreement with the small-angle neutron scattering measurements, the component separation diagram shows nonrandom lateral distribution of the components not only in the gel-fluid mixed phase region, but also in the pure gel and pure fluid regions. A combined diagram of component and state separation is constructed to characterize the lateral distribution of lipid components and gel/fluid state acyl chains in DMPC/DSPC mixtures. While theoretical phase diagrams of two component mixtures can be constructed only in the case of first-order transitions, state and component separation diagrams can be constructed whether or not the system is involved in first-order transition. The effects of interchain interactions on the component and state separation diagrams are demonstrated on three different models. The influences of state and component separation on the in-plane and off-plane membrane reactions are discussed.

Biophys J, October 2002, p. 1820-1833, Vol. 83, No. 4
© 2002 by the Biophysical Society   0006-3495/02/10/1820/14  $2.00


This article has been cited by other articles:


Home page
 Biophys. JHome page
A. Celli, S. Beretta, and E. Gratton
Phase Fluctuations on the Micron-Submicron Scale in GUVs Composed of a Binary Lipid Mixture
Biophys. J., January 1, 2008; 94(1): 104 - 116.
[Abstract] [Full Text] [PDF]

Home page
 Biophys. JHome page
Q. Shi and G. A. Voth
Multi-Scale Modeling of Phase Separation in Mixed Lipid Bilayers
Biophys. J., October 1, 2005; 89(4): 2385 - 2394.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Copyright © 2002 by the Biophysical Society.