Voltage-dependent pore activity of the peptide alamethicin correlated with incorporation in the membrane: salt and cholesterol effects.
Strong aggregation of incorporated alamethicin in the bilayer of lipid vesicles has been observed spectroscopically at aqueous peptide concentrations above a critical value c*. On the other hand, in conventional gating studies with planar lipid films, the onset of conducting pore formation can be characterized by a threshold voltage V.. We present experimental evidence of a direct correspondence between the effects on c* and V. when these parameters are modulated by adding NaCl (to the aqueous medium) or cholesterol (to the lipid moiety). A quantitative analysis supports the idea that the measured aggregation actually results in pore formation, the voltage-dependence being due to an electric field effect on the partition equilibrium of the peptide between the aqueous and the lipid phases.
D000408:Alamethicin; D000900:Anti-Bacterial Agents; D002784:Cholesterol; D002942:Circular Dichroism; D004553:Electric Conductivity; D007473:Ion Channels; D007700:Kinetics; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008563:Membrane Lipids; D008564:Membrane Potentials; D010713:Phosphatidylcholines; D012965:Sodium Chloride
D000900:Anti-Bacterial Agents; D007473:Ion Channels; D008051:Lipid Bilayers; D046911:Macromolecular Substances; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D000408:Alamethicin; D012965:Sodium Chloride; D002784:Cholesterol; C017251:1,2-oleoylphosphatidylcholine