| Autor: |
Tolpekina, T. V., den Otter, W. K., Briels, W. J. |
| Předmět: |
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| Zdroj: |
Journal of Chemical Physics; 12/15/2004, Vol. 121 Issue 23, p12060-12066, 7p, 2 Diagrams, 7 Graphs |
| Abstrakt: |
The formation of a pore in a membrane requires a considerable rearrangement of the amphiphilic molecules about to form the bilayer edge surrounding the pore, and hence is accompanied by a steep increase of the free energy. Recent rupture and conductance experiments suggest that this reshuffling process is also responsible for a small energy barrier that stabilizes “prepores” with diameters of less than 1 nm, rendering both the opening and closing of pores an activated process. We use the potential of mean constraint force method to study this free energy profile, as a function of pore radius, in a coarse grained bilayer model. The calculations show that the free energy rises by (15–20) kT during pore opening, making it an extremely rare nucleation event. Although we do not observe a barrier to pore closure, the results do make the existence of such a barrier plausible. For larger pores we find a smooth transition to Litster’s model, from which a line tension coefficient of about 3.7×10-11 J m-1 is deduced.© 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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