Conductance noise of monazomycin-doped bilayer membranes

Abstract

The conductance noise of the monazomycin pore has been studied by autocorrelation analysis in multi-pore systems. The autocorrelation function could be described by a superposition of two single exponential functions of different time- and voltage-dependence. The slow voltage-dependent correlation time in the range of seconds is assigned to the formation of nonconducting pore precursors. The fast voltage-independent correlation time in the msec range is related to fluctuations in the number of open pores whereby each pore adopts only two conducting states (open and closed). The corresponding correlation amplitude depends on monazomycin concentration and could be related to the single pore conductance. With increasing voltage, a slight increase of the single pore conductance was obtained which is explained on the basis of an electrostatic barrier within the pore. The pore was found to be virtually unselective for different alkali ions (Li, K, Cs).

Monazomycin-induced single channels. I. Characterization of the elementary conductance events.

“…It is generally agreed that the voltage-dependent conductance that monazomycin confers upon lipid bilayer membranes is based on the existence of "channels" or "pores ." The properties ofthe macroscopic conductance (Muller and Finkelstein, 1972a, b) and the observation of excess current noise (Moore and Neher, 1976;Wanke and Prestipino, 1976 ;Kolb, 1979) are consistent with the idea that monazomycin creates metastable, hydrophilic paths connecting the two aqueous solutions that bathe the film .…”

Relaxation studies of ion transport systems in lipid bilayer membranes

“…A number of small or medium-sized hydrophobic peptides and polyenes are known to form oligomeric ion-channels in liquid bilayer membranes, such as alamethicin (Mueller & Rudin, 1968;Eisenberg, Hall & Mead, 1973;Gordon & Haydon, 1976;Mueller, 1976;Boheim & Kolb, 1978), trichotoxin (Boheim, Irmscher & Jung, 1978) or monazomycin (Mueller & Rudin, 1969;Mauro, Nanavati & Heyer, 1972;Muller & Finkelstein, 1972;Bamberg & Janko, 1976;Moore &Neher, 1976;Kolb, 1979). The best-studied example is the dimeric cation-permeable channel formed by the hydrophobic peptide gramicidin A (Mueller & Rudin, 1967;Urry, 1971;Urry et ah 1971;Bamberg & Lauger, 1973;Veatch & Stryer, 1977;Eisenman, Sandblom & Neher, 1978;Andersen & Procopio, 1980).…”

The kinetics of monazomycin-induced voltage-dependent conductance. II. Theory and a demonstration of a form of memory.

“…From the foregoing, it is evident that we will treat the insertion process as rate limiting; this must be true if the rate constant we measure from the exponential portion of conductance rises is indeed a reflection of the insertion process. This assumption is supported by analysis of conductance fluctuations around the steady state (Kolb, 1979;Moore and Neher, 1976). Kolb (1979) reports two detectable processes: one that is fast and voltage independent, the other slower and voltage dependent.…”

“…This assumption is supported by analysis of conductance fluctuations around the steady state (Kolb, 1979;Moore and Neher, 1976). Kolb (1979) reports two detectable processes: one that is fast and voltage independent, the other slower and voltage dependent. Because we have already identified the insertion reaction as the source of the voltage dependence, it must also be the slower process.…”