INTRINSIC RECTIFICATION OF ION FLUX IN ALAMETHICIN CHANNELS - STUDIESWITH AN ALAMETHICIN DIMER

Covalent dimers of alamethicin form conducting structures with gating properties that permit measurement of current-voltage (I-V) relationsh ips during the lifetime of a single channel. These I-V curves demonstr ate that the alamethicin channel is a rectifier that passes current pr eferentially, with voltages of the same sign as that of the voltage th at induced opening of the channel. The degree of rectification depends on the salt concentration; single-channel I-V relationships become al most linear in 3 M potassium chloride. These properties may be qualita tively understood by using Poisson-Nernst-Planck theory and a modeled structure of the alamethicin pore.