Interaction of the general volatile anesthetic Enflurane with bacteriorhodopsin-DPPC proteoliposomes

Homogenous bacteriorhodopsin-DPPC proteoliposomes were characterized and used as a target for the general anesthetic Enflurane. Dose–response curves for the protein and the lipids, in the very same sample, at high (2800) and low (360) lipid: bacteriorhodopsin molar ratios, were compared simultaneously. Above the main phase transition temperature of DPPC, there is no difference between the protein and lipid sensitivities toward the anesthetic. Below the main phase transition temperature of DPPC, the bacteriorhodopsin sensitivity toward Enflurane is much higher than that of lipids. Its dose–response curves reach saturation at anesthetic concentrations where their effect on lipids is barely visible, indicating that bulk lipids do not mediate the anesthetic action.