EFFECTS OF ANESTHETICS ON THE STRUCTURE OF A PHOSPHOLIPID-BILAYER - MOLECULAR-DYNAMICS INVESTIGATION OF HALOTHANE IN THE HYDRATED LIQUID-CRYSTAL PHASE OF DIPALMITOYLPHOSPHATIDYLCHOLINE
Kc. Tu et al., EFFECTS OF ANESTHETICS ON THE STRUCTURE OF A PHOSPHOLIPID-BILAYER - MOLECULAR-DYNAMICS INVESTIGATION OF HALOTHANE IN THE HYDRATED LIQUID-CRYSTAL PHASE OF DIPALMITOYLPHOSPHATIDYLCHOLINE, Biophysical journal, 75(5), 1998, pp. 2123-2134
We report the results of constant temperature and pressure molecular d
ynamics calculations carried out on the liquid crystal (L-alpha) phase
of dipalmitoylphosphatidylcholine with a mole fraction of 6.5% haloth
ane (2-3 MAC). The present results are compared with previous simulati
ons for pure dipalmitoylphosphatidylcholine under the same conditions
(Tu et al., 1995, Biophys. J. 69:2558-2562) and with various experimen
tal data. We have found subtle structural changes in the lipid bilayer
in the presence of the anesthetic compared with the pure lipid bilaye
r: a small lateral expansion is accompanied by a modest contraction in
the bilayer thickness. However, the overall increase in the system vo
lume is found to be comparable to the molecular volume of the added an
esthetic molecules. No significant change in the hydrocarbon chain con
formations is apparent. The observed structural changes are in fair ag
reement with NMR data corresponding to low anesthetic concentrations.
We have found that halothane exhibits no specific binding to the lipid
headgroup or to the acyl chains. No evidence is obtained for preferen
tial orientation of halothane dynamics of the lipid-bound halothane mo
lecules appears to et al., 1995.