Alexander A Sobko

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Introducing a charged group near the N-terminus of gramicidin A (gA) is supposed to suppress its ability to form ion channels by restricting its head-to-head dimerization. The present study dealt with the activity of [Lys1]gA, [Lys3]gA, [Glu1]gA, [Glu3]gA, [Lys2]gA, and [Lys5]gA in model membrane systems (planar lipid bilayers and liposomes) and(More)
The channel activity of colicin E1 was studied in planar lipid bilayers and liposomes. Colicin E1 pore-forming activity was found to depend on the curvature of the lipid bilayer, as judged by the effect on channel activity of curvature-modulating agents. In particular, the colicin-induced trans-membrane current was augmented by lysophosphatidylcholine and(More)
An increase in the expression of the delayed rectifier current (I(K)) has been shown to correlate with mitogenesis in many cell types. However, pathways involved in the upregulation of I(K) by growth factors in oligodendroglial progenitors (OPs) have not been well-elucidated. In this study, we found that treatment with platelet-derived growth factor (PDGF)(More)
A limited decrease in mitochondrial membrane potential can be beneficial for cells, especially under some pathological conditions, suggesting that mild uncouplers (protonophores) causing such an effect are promising candidates for therapeutic uses. The great majority of protonophores are weak acids capable of permeating across membranes in their neutral and(More)
Chemical modification and photodynamic treatment of the colicin E1 channel-forming domain (P178) in vesicular and planar bilayer lipid membranes (BLMs) was used to elucidate the role of tryptophan residues in colicin E1 channel activity. Modification of colicin tryptophan residues by N-bromosuccinimide (NBS), as judged by the loss of tryptophan(More)
Colicin E1 belongs to a group of bacteriocins whose cytotoxicity toward Escherichia coli is exerted through formation of ion channels that depolarize the cytoplasmic membrane. The lipid dependence of colicin single-channel conductance demonstrated intimate involvement of lipid in the structure of this channel. The colicin formed "small" conductance(More)
Ion-channel activity of a series of gramicidin A analogues carrying charged amino-acid sequences on the C-terminus of the peptide was studied on planar bilayer lipid membranes and liposomes. It was found that the analogue with the positively charged sequence GSGRRRRSQS forms classical cationic pores at low concentrations and large unselective pores at high(More)
According to recent data, gramicidin A analogues having positively charged amino acid sequences at the C-termini exhibit two types of channel activity in lipid membranes: classical cation-selective channels and large unselective pores. The induction of unselective pores was shown here to strongly depend on the redox state of the membrane-bathing solution,(More)
The channel-forming activity of gramicidin A derivatives carrying positively charged amino acid sequences at their C-termini was studied on planar bilayer lipid membranes and liposomes. We showed previously (FEBS Lett., 2005, vol. 579, pp. 5247–5252) that, at low concentrations, these peptides form classical cation-selective pores typical of gramicidin A,(More)
Based on the model of a toroidal protein-lipid pore, the effect of calcium ions on colicin E1 channel was predicted. In electrophysiological experiments Ca2+ suppressed the activity of colicin E1 channels in membranes formed of diphytanoylphosphatidylglycerol, whereas no desorption of the protein occurred from the membrane surface. The effect of Ca2+ was(More)