Monazomycin-induced single channels. II. Origin of the voltage dependence of the macroscopic conductance
The voltage dependence of the conductance induced induced in thin lipid membranes by monazomycin is shown here to be caused by voltage-dependent variations in the frequency of channel openings. We also experimentally demonstrate certain interesting properties of the channel activity that are predicted by a chemical kinetic model (Muller and Peskin, 1981), which successfully describes the macroscopic conductance. We conclude that two parallel mechanisms--one autocatalytic, the other simple mass action--exist that allow monazomycin to enter (or leave) the membrane so that the monazomycin molecules can be in a position to form channels.