Search results for " and Transporters"
showing 3 items of 3 documents
Regulation of Calcium Channel Activity by Lipid Domain Formation in Planar Lipid Bilayers
2003
The sarcoplasmic reticulum channel (ryanodine receptor) from cardiac myocytes was reconstituted into planar lipid bilayers consisting of 1-palmitoyl-2-oleoyl-phosphatidylethanolamine (POPE) and 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) in varying ratios. The channel activity parameters, i.e., open probability and average open time and its resolved short and long components, were determined as a function of POPE mole fraction (X(PE)) at 22.4 degrees C. Interestingly, all of these parameters exhibited a narrow and pronounced peak at X(PE) approximately 0.80. Differential scanning calorimetric measurements on POPE/POPC liposomes with increasing X(PE) indicated that the lipid bilayer ente…
Interaction of Heparins and Dextran Sulfates with a Mesoscopic Protein Nanopore
2009
A mechanism of how polyanions influence the channel formed by Staphylococcus aureus alpha-hemolysin is described. We demonstrate that the probability of several types of polyanions to block the ion channel depends on the presence of divalent cations and the polyanion molecular weight and concentration. For heparins, a 10-fold increase in molecular weight decreases the half-maximal inhibitory concentration, IC(50), nearly 10(4)-fold. Dextran sulfates were less effective at blocking the channel. The polyanions are significantly more effective at reducing the conductance when added to the trans side of this channel. Lastly, the effectiveness of heparins on the channel conductance correlated wi…
Anomalous surface diffusion of protons on lipid membranes.
2014
AbstractThe cellular energy machinery depends on the presence and properties of protons at or in the vicinity of lipid membranes. To asses the energetics and mobility of a proton near a membrane, we simulated an excess proton near a solvated DMPC bilayer at 323 K, using a recently developed method to include the Grotthuss proton shuttling mechanism in classical molecular dynamics simulations. We obtained a proton surface affinity of −13.0 ± 0.5 kJ mol−1. The proton interacted strongly with both lipid headgroup and linker carbonyl oxygens. Furthermore, the surface diffusion of the proton was anomalous, with a subdiffusive regime over the first few nanoseconds, followed by a superdiffusive re…