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A lipid vesicle system for probing voltage‐dependent peptide–lipid interactions: Application to alamethicin channel formation
Author(s) -
Woolley G. Andrew,
Deber Charles M.
Publication year - 1989
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360280127
Subject(s) - alamethicin , chemistry , valinomycin , vesicle , ionophore , membrane potential , biophysics , melittin , voltage gated potassium channel , calcium , phosphatidylcholine , gating , lipid bilayer , potassium , membrane , biochemistry , phospholipid , organic chemistry , biology
Abstract A membrance potential is shown to be established in phosphatidylcholine/cholesterol unilamellar vesicles using valinomycin in conjunction with a potassium ion gradient; this potential is monitored using the externally added fluorescent dye Safranine O. In the same system, transmembrance calcium fluxes are then detected using the (internally trapped) fluorescent dye Quin‐2. The calcium‐transport behavior of the channel‐forming peptide alamethicin is shown to be potential dependent in this system, in contrast to calcium transport by the ionophore Br‐A23187, which is unaffected by the potential. The observation of this potential‐dependent behavior for alamethicin suggests that this vesicle system may be suitable for direct spectroscopic observation of the voitage‐gating process.