Ionophoric activity of truncated gramicidin A analogue in phospholipid bilayers and mitochondrial and erythrocyte membranes |
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Authors: | E. A. Dutseva E. A. Kotova Yu. N. Antonenko |
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Affiliation: | (1) Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Vorob’evy gory, Moscow, 119991, Russia;(2) School of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Vorob’evy gory, Moscow, 119991, Russia |
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Abstract: | Ionophoric activities of an N-terminus truncated gramicidin A (gA) analogue (mini-gramicidin) and its covalent dimer were studied in planar bilayer phospholipid membranes (BLM) using macroscopic current measurements (at high concentrations of the peptides) and single-channel recordings. As with gA-induced currents, mini-gramicidin-stimulated macroscopic currents through BLM underwent sensitized photoinactivation, i.e. were suppressed after irradiation with visible light in the presence of a photosensitizer generating singlet oxygen. The sensitivity of the tested compounds to photoinactivation descended in the following order: minigramicidin dimer > mini-gramicidin monomer > gA. The data from single-channel measurements and kinetic analysis of flash-induced photoinactivation obtained at different levels of macroscopic currents suggest that mini-gramicidin and its covalent dimer induce a variety of conducting states; their ratio depends on membrane thickness. Analysis of natural (mitochondrial and erythrocyte) membranes established that ionophoric activities of mini-gramicidin and its covalent dimer depend essentially on the membrane type. |
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