The role of transmembrane potential and defects on permeabilization of lipid bilayers by alamethicin, an ion channels forming peptide

dc.contributor.authorSu, Z. F.
dc.contributor.authorShodiev, M.
dc.contributor.authorLeitch, J.J.
dc.contributor.authorAbbasi, F.
dc.contributor.authorLipkowski, J.
dc.date.accessioned2022-01-28T16:34:45Z
dc.date.available2022-01-28T16:34:45Z
dc.date.createdMay-18
dc.degree.departmentElectrochemical Technology Centreen
dc.degree.departmentDepartment of Chemistryen
dc.description.abstractThe insertion and ion-conducting channel properties of alamethicin reconstituted into a 1,2-di-O-phytanyl-sn-glycero-3-phosphocholine bilayer floating on the surface of a gold (111) electrode modified with a 1-thio-β-d-glucose (β-Tg) self-assembled monolayer were investigated using a combination of electrochemical impedance spectroscopy (EIS) and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS). The hydrophilic β-Tg monolayer separated the bilayer from the gold substrate and created a water-rich spacer region, which better represents natural cell membranes. The EIS measurements acquired information about the membrane resistivity (a measure of membrane porosity), and the PM-IRRAS experiments provided insight into the conformation and orientation of the membrane constituents as a function of the transmembrane potential. The results showed that the presence of alamethicin had a small effect on the conformation and orientation of phospholipid molecules within the bilayer for all studied potentials. In contrast, the alamethicin peptides assumed a surface state, where the helical axes adopted a large tilt angle with respect to the surface normal, at small transmembrane potentials, and inserted into the bilayer at sufficiently negative transmembrane potentials forming pores, which behaved as barrel-stave ion channels for ionic transport across the membrane. The results indicated that insertion of alamethincin peptides into the bilayer was driven by the dipole–field interactions and that the transitions between the inserted and surface states were electrochemically reversible. Additionally, the EIS measurements performed on phospholipid bilayers without alamethicin also showed that the application of negative transmembrane potentials introduces defects into the bilayer. The membrane resistances measured in both the absence and presence of alamethicin show similar dependencies on the electrode potential, suggesting that the insertion of the peptide may also be assisted by the electroporation of the membrane. The findings in this study provide new insights into the mechanism of alamethicin insertion into phospholipid bilayers.en_US
dc.description.sponsorshipNatural Sciences and Engineering Research Council of Canada (NSERC)en_US
dc.identifier.urihttps://hdl.handle.net/10214/26748
dc.language.isoenen_US
dc.publisherACS Publicationen_US
dc.rights.licenseAll items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectalamethicinen_US
dc.subjection channelen_US
dc.subjectEISen_US
dc.subjectPM-IRRASen_US
dc.titleThe role of transmembrane potential and defects on permeabilization of lipid bilayers by alamethicin, an ion channels forming peptideen_US
dc.typeArticleen_US
dcterms.relationZhangFei Su, Muzaffar Shodiev, J. Jay Leitch, Fatemeh Abbasi, and Jacek Lipkowski, The role of transmembrane potential and defects on permeabilization of lipid bilayers by alamethicin, an ion channels forming peptide, Langmuir, 2018,34,6249-6260. https://doi.org/10.1021/acs.langmuir.8b00928.en_US

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