Electrostatic potential barrier in asymmetric planar lipopolysaccharide/phospholipid bilayers probed with the valinomycin-K+ complex.
Using the carrier-ion complex valinomycin-K+, current/voltage (I/U) characteristics were registered for planar asymmetric lipid bilayers composed on one side of a phospholipid mixture and on the other side of rough mutant lipopolysaccharide. This system resembles the lipid matrix of the outer membrane of Gram-negative bacteria. The evaluation of the current/voltage curves yielded a highly asymmetric electrical potential barrier. The total potential difference between the phospholipid and the lipopolysaccharide was -85 mV, a result which cannot be explained by contributions of Gouy-Chapman potentials alone. The possible contribution of dipole potentials and influences of headgroup effects are discussed. It is shown that the asymmetry of the I/U-characteristic results from the differences of the surface charge densities of the two monolayers but not from those of the states of order of their hydrocarbon chains.
Seydel
U
U
Forschungsinstitut Borstel, Borstel, Bundesrepublik Deutschland.
Eberstein
W
W
Schröder
G
G
Brandenburg
K
K
D002240:Carbohydrate Sequence; D004553:Electric Conductivity; D004926:Escherichia coli; D008051:Lipid Bilayers; D008070:Lipopolysaccharides / Q000737:chemistry*; D008433:Mathematics; D008564:Membrane Potentials; D008962:Models, Theoretical; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000737:chemistry*; D011188:Potassium; D014634:Valinomycin
D008051:Lipid Bilayers; D008070:Lipopolysaccharides; D010743:Phospholipids; D014634:Valinomycin; D011188:Potassium