Electric field dependence of alamethicin channels.
Circular dichroism (CD) of alamethicin embedded in vesicular membranes from outside, and its change, upon imposing Donnan potentials across the membrane, was measured. The changes in CD suggested a decrease in a helicity and increase in beta structure with the membrane potential positive inside and vice versa when the potential was positive on the outer side of the vesicles from where the alamethicin was inserted into the membrane. The Donnan potential was created by entrapping the polyacrylate (PA-) in the vesicles and changing the salt concentration outside or by adding different concentrations of PA- or polyethyleneimide (PEI+) at the outside of vesicles with 2 x 10(-5) M salt inside. The effect of the potential on the CD spectra and thus the alamethicin conformation is independent on the type of the polyelectrolyte employed for the Donnan potential generation.
Department of Membrane Research, Weizmann Institute of Science, Rehovot, Israel.
V
V
Brumfeld
I R
IR
Miller
D000408:Alamethicin; D000900:Anti-Bacterial Agents; D002942:Circular Dichroism; D007473:Ion Channels / Q000502:physiology / Q000648:ultrastructure*; D008563:Membrane Lipids; D008564:Membrane Potentials; D008565:Membrane Proteins / Q000648:ultrastructure; D010713:Phosphatidylcholines; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence
D000900:Anti-Bacterial Agents; D007473:Ion Channels; D008563:Membrane Lipids; D008565:Membrane Proteins; D010713:Phosphatidylcholines; D000408:Alamethicin