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We have studied the phenomenological origin of 1/f noise in a solute-specific bacterial ion channel, maltoporin. We show that after excision of small, but resolvable stepwise changes in the recordings of the current through a single open channel, the 1/f noise component disappears and the channel exhibits noise that is "white" below 100 Hz. Combined with(More)
BACKGROUND Multi-drug resistant (MDR) infections have become a major concern in hospitals worldwide. This study investigates membrane translocation, which is the first step required for drug action on internal bacterial targets. beta-lactams, a major antibiotic class, use porins to pass through the outer membrane barrier of Gram-negative bacteria. Clinical(More)
Gram-negative bacteria are responsible for a large proportion of antibiotic-resistant bacterial diseases. These bacteria have a complex cell envelope that comprises an outer membrane and an inner membrane that delimit the periplasm. The outer membrane contains various protein channels, called porins, which are involved in the influx of various compounds,(More)
We investigate the permeability of lipid membranes for fluorescence dyes and ions. We find that permeability reaches a maximum close to the chain melting transition of the membranes. Close to transitions, fluctuations in area and compressibility are high, leading to an increased likelihood of spontaneous lipid pore formation. Fluorescence correlation(More)
BACKGROUND We investigated the encapsulation mechanism of enzymes into liposomes. The existing protocols to achieve high encapsulation efficiencies are basically optimized for chemically stable molecules. Enzymes, however, are fragile and encapsulation requires in addition the preservation of their functionality. Using acetylcholinesterase as a model, we(More)
The temperature-dependent ion conductance of OmpC, a major outer membrane channel of Escherichia coli, is predicted using all-atom molecular dynamics simulations and experimentally verified. To generalize previous results, OmpC is compared to its structural homolog OmpF at different KCl concentrations, pH values, and a broad temperature range. At low salt(More)
Background: Multi-drug resistant (MDR) infections have become a major concern in hospitals worldwide. This study investigates membrane translocation, which is the first step required for drug action on internal bacterial targets. b-lactams, a major antibiotic class, use porins to pass through the outer membrane barrier of Gram-negative bacteria. Clinical(More)
BACKGROUND Lectins are carbohydrate-binding proteins which potentially bind to cell surface glycoconjugates. They are found in various organisms including fungi. A lectin from the mushroom Xerocomus chrysenteron (XCL) has been isolated recently. It shows insecticidal activity and has antiproliferative properties. RESULTS As the monosaccharide binding(More)
We study fluctuations in ion conductance and enzymatic rates of the sugar-specific channel-forming membrane protein, Maltoporin, at the single-molecule level. Specifically, we analyze time-persistent deviations in the transport parameters of individual channels from the multichannel averages and discuss our findings in the context of static disorder in(More)
The role of major porin OmpPst1 of Providencia stuartii in antibiotic susceptibility for two carbapenems is investigated by combining high-resolution conductance measurements, liposome swelling, and microbiological assays. Reconstitution of a single OmpPst1 into a planar lipid bilayer and measuring the ion current, in the presence of imipenem, revealed a(More)