Monazomycin-induced single channels. II. Origin of the voltage dependence of the macroscopic conductance.

Abstract

The voltage dependence of the conductance 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 , 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 .

Alamethicin. A rich model for channel behavior

“…The voltage-dependent conductance induced by monazomycin has many similarities to the alamethicin-induced conductance. But the monazomycin gating charge is probably a formal positive charge rather than a structural dipole (Andersen Muller and Andersen, 1982). , .…”

Short-Term Facilitation-Then-Depression Enables Adaptive Processing of Sensory Inputs by Ion Channels in Biomolecular Synapses

“…A DPhPC membrane formed between droplets with 20 μg mL –1 Mz exhibits a higher switching threshold (∼110 mV) compared to one constructed from porcine brain total lipid extract (BTLE) with only 1 μg mL –1 Mz in each droplet (∼55 mV) (Figure S3b,c). Mz insertion properties are documented to be highly concentration and lipid dependent. ,,,, Mz in BTLE showed permanent insertion and produced currents that were beyond the measurement capabilities of our devices at 20 μg mL –1 , so 1 μg mL –1 was chosen to produce synapses with similar current densities and insertion thresholds to the other devices.…”

“…Herein, we report a biomolecular device consisting of an insulating lipid membrane doped with monazomycin (Mz) (Figure a) that is capable of emulating multiple forms of STP concurrently (Figure b)including facilitation-then-depression under constant stimulus frequency and augmentation that persists after stimulation ends. Mz is a voltage-dependent, pore-forming antibiotic (chemical formula: C 72 H 133 NO 22 , exact 3D conformation unknown) that forms ion channels through lipid membranes (3–5 nm thick) at suprathreshold voltages. − Collectively, the formation of Mz ion channels produces nonlinear, voltage-activated memristive ion currents through the membrane (Figures c and S1a) that disappear in its absence (Figure S1b).…”

Switchable foldamer ion channels with antibacterial activity

“…The increase in conductance over time may be due to slow insertion of the foldamer into the membrane, a process that is accelerated as the potential difference increases (especially for negative potentials). 45 …”

“…The increase in conductance over time may be due to slow insertion of the foldamer into the membrane, a process that is accelerated as the potential difference increases (especially for negative potentials). 45 The blue product from the addition of CuCl to 2 was also assessed using PBC experiments. Under the same conditions used for Cu(II) [2]Cl 2 , Cu(II) [2]Cl$HCO 3 showed a mixture of behaviours.…”