Kinetics of carrier-mediated ion transport in two new types of solvent-free lipid bilayers.
In contrast with the usual glyceryl-monooleate/decane (GMO-D) bilayer lipid membranes, new membranes, formed from a mixture of GMO in squalene (GMO-S) or from a mixture of GMO in triolein (GMO-T), seem to be almost solvent free. Our results from voltage-jump relaxation studies, using these "solvent-free" membranes with the homologue carriers, nonactin, monactin, dinactin, trinactin, and tetranactin, are compared with the corresponding ones for GMO-D membranes. With all homologues, solvent-free membranes show an increase of the free carrier translocation rate, ks, by a factor of 2.5, a decrease in the dissociation rate constant of the complex, kDi, by a factor of 1.5 and no significant change in its formation rate constant, kRi. However, the principal effect of the absence of solvent in these membranes is an increase by a factor of approximately 10 of the translocation rate constant for moving the complex across the membrane, kis. This increase varies regularly from a factor of 7-15 with decreasing carrier size, and is always larger for GMO-T than for GMO-S membranes. These solvent-free effects are interpreted in terms of modifications of electrostatic and hydrophobic energy profiles in the membrane.
D000641:Ammonia / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000031:analogs & derivatives / Q000378:metabolism; D001692:Biological Transport; D004558:Electric Stimulation; D005989:Glycerides; D007700:Kinetics; D008051:Lipid Bilayers / Q000378:metabolism*; D018942:Macrolides; D008433:Mathematics; D013185:Squalene; D014304:Triolein
D000900:Anti-Bacterial Agents; D005989:Glycerides; D008051:Lipid Bilayers; D018942:Macrolides; D014304:Triolein; D000641:Ammonia; D013185:Squalene; C005953:monoolein; C050476:nonactin