8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Tue 611:23-14:00P10.7Anesthetic molecules embedded in a lipid membrane. Acomputer simulation studyMária Darvas 11 ELTE University, Pázmány stny. 1/a, H-1117, Budapest, HungaryThe effect of four general anesthetic molecules, i. e. , chloroform, halothane, diethyl ether andenflurane on the properties of a fully hydrated dipalmitoylphosphatidylcholine (DPPC) membraneis studied in detail by long molecular dynamics simulations. Further, to address the problem ofpressure reversal the effect of pressure on the anesthetic containing membranes is also investigated.In order to ensure sufficient equilibration and adequate sampling, the simulations performed havebeen at least an order of magnitude longer than the studies reported previously in the literature onsimilar systems. The obtained results can help in resolving several long-standing contradictionsconcerning the effect of anesthetics. Some of these contradictions are resulting from the far tooshort simulation time used in several previous studies. More importantly, a number of seemingcontradictions are found to originate from the fact that different anesthetic molecules affect themembrane structure differently in several respects. In particular, halothane, being able to weaklyhydrogen bound to the ester group of the lipid tails, is found to behave in a markedly different waythan the other three molecules considered. Besides, we also found two properties that are clearlyaffected by all the four anesthetic molecules tested here in the same way, and this effect is revertedby the increase of pressure. The first of these two effects is a lateral expansion, accompanied bythe increase of the volume of the membrane in the presence of anesthetics, whereas the other oneis the local disorder induced by the anesthetic molecules on the lipid tails at their close vicinity.7