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Fast flip–flop of halogenated cobalt bis(dicarbollide) anion in a lipid bilayer membrane

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Abstract

Transmembrane translocation (flip–flop) of cobalt bis(dicarbollide) (COSAN) anions, elicited by application of a voltage-jump across the lipid bilayer membrane, manifested itself in monoexponential electrical current transients in the microsecond time scale. Halogenation of COSAN led to multi-fold acceleration of the flip–flop, the effect increasing with the molecular weight of the halogens. The exception was a fluorinated analog which exhibited slowing of the translocation kinetics. Measurements of the fluorescence ratio of the dye di-4-ANEPPS in lipid vesicles showed significant differences in the adsorption of studied hydrophobic anions. Based on these data, it can be concluded that COSAN and COSAN-F2 were located on the surface of the lipid membrane in the cisoid conformation increasing the dipole potential of the lipid membrane, while other halogenated COSAN analogs were adsorbed in the transoid conformation. Differences in the flip–flop kinetics of COSAN analogs were attributed to variation in the molecular volume of the anions and their orientation on the membrane surface.

Graphical abstract: Fast flip–flop of halogenated cobalt bis(dicarbollide) anion in a lipid bilayer membrane

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Publication details

The article was received on 22 Jun 2017, accepted on 17 Aug 2017 and first published on 07 Sep 2017


Article type: Paper
DOI: 10.1039/C7CP04207H
Citation: Phys. Chem. Chem. Phys., 2017, Advance Article
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    Fast flip–flop of halogenated cobalt bis(dicarbollide) anion in a lipid bilayer membrane

    T. I. Rokitskaya, I. D. Kosenko, I. B. Sivaev, Y. N. Antonenko and V. I. Bregadze, Phys. Chem. Chem. Phys., 2017, Advance Article , DOI: 10.1039/C7CP04207H

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