Structures of amphotericin B-cholesterol complex.

The structures of amphotericin B-cholesterol complex that forms a channel in a lipid membrane were analysed by molecular mechanics calculations. The symmetric complex consisting of eight rigid antibiotic and cholesterol molecules was considered. The presence of a continuous set of low-energy states of the complex with different values of the channel diameter was shown. These states are characterized by significant tilt of the amphotericin planes to the radial axis of the channel and by strong interaction between the charged ammonium and carboxyl groups of the antibiotic. Changes of the channel diameter may result in changes in pore permeability.