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Electrophysiological properties of Amphotericin B (AmB) pores in lipid bilayers have been studied extensively with the purpose of understanding membrane transport phenomena1. Also because AmB has a clinical relevance, it is the drug of choice for treating systemic fungal infection in spite of having strong collateral toxicity. One of the interests has been to determine the number of molecules involved in the formation of the ion channels reported. Reports in the literature present values that go from 4 to 12. This has been explained because channels with different conductivities are formed2 and therefore the determination with macroscopic currents corresponds to an average of the population of different channels. In this work, we determined the number of molecules of AmB involved in the formation of each one of these pores by single channel methods3. Our results show that different types of channels are formed by the same number of AmB molecules, which is very interesting, considering that these channels have certainly different radius. This suggests a model in which AmB pores are not the only component of the pores, having either lipids in a toroidal structure or sterols in a barrel structure.References[1] A. Cass, A Finkelstein & V Krespi. The Ion Permeability Induced in Thin Lipid Membranes by the Polyene Antibiotics Nystatin and Amphotericin B, J. Gen. Physiol. 56, 100, (1970).[2] B. Venegas, J. Gonzalez-Damian, H. Celis & I. Ortega-Blake. Amphotericin B Channels in the Bacterial Membrane: Role of Sterol and Temperature, Biophysical Journal 85, 2323, (2003).[3] B. Sakmann & E. Neher, Single-Channel Recording, Kluwer Academic/Plenum Publishers, N.Y. (1995). |
