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Dynamics, pore formation

Gurtovenko, A.A., Vattulainen, I. Pore formation coupled to ion transport through lipid membranes as induced by transmembrane ionic charge imbalance atomistic molecular dynamics study. J. Am. Chem. Soc. 2005, 127, 17570-1. [Pg.20]

Tolpekina, T.V., den Otter, W.K., Briels, W.J. Nucleation free energy of pore formation in an amphiphilic bilayer studied by molecular dynamics simulations. J. Chem. Phys. 2004, 121, 12060-6. [Pg.20]

Ferain, E., and Legras, R., Hack-etched membrane-dynamics of pore formation. Nucl. Instrum. Methods B 84, 539 (1993). [Pg.200]

The pore formation mechanism presented in Fig. 7 (45) is appealing for many reasons. It illustrates the significance of thermal fluctuations, because the pore is indeed induced by fluctuations in spontaneous salt ion concentrations in the vicinity of the membrane. Furthermore, the pore mediated ion leakage mechanism is very rapid, and it occurs in a collective manner through redistribution and diffusion of lipids around the pore. Also, recent data indicate that the pores also mediate flip-flop events across a membrane (46), which provides one plausible mechanism for lipid translocation, which in turn is of central importance in processes such as programmed cell death. Other dynamic processes in lipid systems are expected to be equally complex, which highlights the importance to understand the interplay between thermal fluctuations, physiologic conditions, and collective phenomena. [Pg.2245]

Generally, the effectiveness of the separation is determined not by the membrane itself, but rather by the formation of a secondary or dynamic membrane caused by interactions of the solutes and particles with the membrane. The buildup of a gel layer on the surface of an ultrafiltration membrane owing to rejection of macromolecules can provide the primary separation characteristics of the membrane. Similarly, with colloidal suspensions, pore blocking and bridging of... [Pg.75]

Fig. 8 Proposed model for gramicidin S in a membrane according to the orientational constraints obtained from and N-NMR. The upright backbone alignment (r 80°) and slant of the /3-sheets (p -45°) are compatible with the formation of an oligomeric /3-barrel that is stabilized by hydrogen bonds (dotted lines). A The oligomer is depicted sideways from within the lipid bilayer interior (showing only backbone atoms for clarity, but with hydrophobic side chains added to one of the monomers). Atomic coordinates of GS were taken from a monomeric structure [4], and the two DMPC lipid molecules are drawn to scale (from a molecular dynamics simulation coordinate file). The bilayer cross-section is coloured yellow in its hydrophobic core, red in the amphiphilic regions, and light blue near the aqueous surface. B Illustrates a top view of the putative pore, although the number of monomers remains speculative... Fig. 8 Proposed model for gramicidin S in a membrane according to the orientational constraints obtained from and N-NMR. The upright backbone alignment (r 80°) and slant of the /3-sheets (p -45°) are compatible with the formation of an oligomeric /3-barrel that is stabilized by hydrogen bonds (dotted lines). A The oligomer is depicted sideways from within the lipid bilayer interior (showing only backbone atoms for clarity, but with hydrophobic side chains added to one of the monomers). Atomic coordinates of GS were taken from a monomeric structure [4], and the two DMPC lipid molecules are drawn to scale (from a molecular dynamics simulation coordinate file). The bilayer cross-section is coloured yellow in its hydrophobic core, red in the amphiphilic regions, and light blue near the aqueous surface. B Illustrates a top view of the putative pore, although the number of monomers remains speculative...
The increase of pore size with increasing amount of solvent can also be monitored with dynamic DSC-measurements. An endothermic peak at T=7 °C, corresponding to the melting point of crystalline cyclohexane, is observed in the opaque samples after the phase separation resulting from the formation of dispersed cyclohexane droplets (Fig. 53). [Pg.238]


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