Experimental conditions for the discovery of single ion channels in lipid membranes modified by polyene antibiotics are described for the first time. In the presence of polyenes, the increase in the membrane current is accompanied by discrete jumps. The amount of conductivity and concentration of the antibiotic required to obtain a single channel depend on the type and concentration of the electrolyte washing the membrane. The properties of the channel in the conducting state depend on the electrolyte and also on the time assembly of the channels. In solutions of alkali metal chlorides with the same activity of these salts, the channel conductivity increases in a row: Li+, Na+, K+, Cs+, and in solutions of potassium chloride in the row: I-, F-, NO-3, Br-, Cl-. The channel conductivity increases with the crystal radius of the cation. It is showed that the amphotericin channel has a conductivity of 3.5 pS in a solution of 10-1 M KCI. The nystatin channel has a conductivity of 1.4 pS. The channels make reversible transitions from the open state to the closed state. The frequency of these transitions depends on the type of electrolyte. The minimum conductivity had been a mycoheptin and levorin channels (0.2-0.3 pS). Of the studied antibiotics, only the aromatic antibiotic levorin A2 is sensitive to fluctuations in the membrane potential.
polyene antibiotics, chemical structure, lipid membrane, ion channel, discrete conductivity, channel states
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