A simple method for the determination of the pore radius of ion channels in planar lipid bilayer membranes

Krasilnikov, Oleg V.; Sabirov, Ravshan Z.; Ternovsky, Vadim I.; Merzliak, P G; Muratkhodjaev, Javdat N.

doi:10.1111/j.1574-6968.1992.tb05891.x

Cited by 185 publications

(155 citation statements)

References 19 publications

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“…3 top, two single channel recordings, minus avidin͒. After adding avidin, the results show that the complex between avidin:bT-poly͓dC͔ 30 , but not avidin:bT-poly͓dC͔ 20 , occluded the pore virtually indefinitely ͓Fig. 3͑a͒, plus avidin͔.…”

Section: B Location Of Polynucleotide Transport Barriermentioning

confidence: 96%

“…In addition, Krasilnikov and others used PEGs to estimate the radii of ion channels from the ability of size-selected PEGs to partition into the channel pore. 11,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] Protein translocation across membranes, which plays a key role in many biological processes, can be facilitated by ion channels. [37][38][39] Other biomolecules can be detected as they transport through ion channels.…”

Section: Introductionmentioning

confidence: 99%

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Probing single nanometer-scale pores with polymeric molecular rulers

Henrickson¹,

DiMarzio

Wang³

et al. 2010

The Journal of Chemical Physics

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We previously demonstrated that individual molecules of single-stranded DNA can be driven electrophoretically through a single Staphylococcus aureus ␣-hemolysin ion channel. Polynucleotides thread through the channel as extended chains and the polymer-induced ionic current blockades exhibit stable modes during the interactions. We show here that polynucleotides can be used to probe structural features of the ␣-hemolysin channel itself. Specifically, both the pore length and channel aperture profile can be estimated. The results are consistent with the channel crystal structure and suggest that polymer-based "molecular rulers" may prove useful in deducing the structures of nanometer-scale pores in general.

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Section: B Location Of Polynucleotide Transport Barriermentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Probing single nanometer-scale pores with polymeric molecular rulers

Henrickson¹,

DiMarzio

Wang³

et al. 2010

The Journal of Chemical Physics

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“…We used poly(ethylene glycol) (PEG) of 400, 1450, 3400 and 4600 Da (Sigma); 600 Da (Riedel de Haën); and 1000, 2000 and 3000 Da (Loba Chemie). In experiments using physiological concentration of electrolytes (0.15 M), the hydrodynamic radii of nonelectrolytes (taken from [17,18,29]) were: 0.26 ± 0.02 glycerol, 0.37 ± 0.02 glucose, 0.47 ± 0.02 sucrose, 0.70 ± 0.04 nm PEG 400, 0.80 ± 0.04 nm PEG 600, 0.94 ± 0.04 nm PEG 1000, 1.05 ± 0.04 nm PEG 1450, 1.22 ± 0.04 nm PEG 2000, 1.44 ± 0.04 nm PEG 3000, 1.65 ± 0.03 nm PEG 3400, and 2.1 ± 0.03 nm PEG 4600. At higher concentration of KCl (0.7 M) used in channel-sizing BLM experiments, the PEG radii were taken as approximately 98% of those noted above, based on an observation (R.R.…”

Section: Chemicalsmentioning

confidence: 99%

Pore-forming properties of proteolytically nicked staphylococcal ⋅-toxin: the ion channel in planar lipid bilayer membranes

Krasilnikov

Merzlyak

Yuldasheva

et al. 1997

Medical Microbiology and Immunology

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Staphylococcal alpha-toxin is a single-chain protein with a molecular mass of 33.2 kDa, which can form large water-filled pores both in lipid bilayers and in erythrocyte membranes. Limited proteolysis of the purified toxin with proteinase K led to time-dependent changes of all the functional features of the channels formed by the toxin. Single-channel conductance in planar bilayers was decreased about threefold. The anion selectivity of the channel was replaced with cation selectivity and the asymmetry in the current-voltage relationship of the channel became more pronounced. At the same time the nicked toxin kept its full ability to form ion channels in lipid bilayers, although it lost a considerable part of its hemolytic activity. In planar bilayers and in erythrocyte membranes, the proteolytically nicked toxin actually formed channels with a slightly smaller diameter (approximately 1.2 times) than that formed by the native toxin. This decrease was not marked enough to explain changes in the biological effects of the nicked toxin. The change in channel selectivity induced by the cleavage is considered to be the major determinant of the changes in the biological effects of the nicked toxin.

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“…Polyethylene glycols (PEGs) in water solutions obey the viscosity law for random coils [49][50][51] and act as a ''hard sphere'' [52]. These organic nonelectrolytes should exhibit no coulombic interaction with the ion channel wall.…”

Section: Introductionmentioning

confidence: 99%

ATP hydrolysis-dependent asymmetry of the conformation of CFTR channel pore

2011

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Despite substantial efforts, the entire cystic fibrosis transmembrane conductance regulator (CFTR) protein proved to be difficult for structural analysis at high resolution, and little is still known about the actual dimensions of the anion-transporting pathway of CFTR channel. In the present study, we therefore gauged geometrical features of the CFTR Cl(-) channel pore by a nonelectrolyte exclusion technique. Polyethylene glycols with a hydrodynamic radius (R (h)) smaller than 0.95 nm (PEG 300-1,000) added from the intracellular side greatly suppressed the inward unitary anionic conductance, whereas only molecules with R (h) ≤ 0.62 nm (PEG 200-400) applied extracellularly were able to affect the outward unitary anionic currents. Larger molecules with R (h) = 1.16-1.84 nm (PEG 1,540-3,400) added from either side were completely excluded from the pore and had no significant effect on the single-channel conductance. The cut-off radius of the inner entrance of CFTR channel pore was assessed to be 1.19 ± 0.02 nm. The outer entrance was narrower with its cut-off radius of 0.70 ± 0.16 nm and was dilated to 0.93 ± 0.23 nm when a non-hydrolyzable ATP analog, 5'-adenylylimidodiphosphate (AMP-PNP), was added to the intracellular solution. Thus, it is concluded that the structure of CFTR channel pore is highly asymmetric with a narrower extracellular entrance and that a dilating conformational change of the extracellular entrance is associated with the channel transition to a non-hydrolytic, locked-open state.

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A simple method for the determination of the pore radius of ion channels in planar lipid bilayer membranes

Cited by 185 publications

References 19 publications

Probing single nanometer-scale pores with polymeric molecular rulers

Probing single nanometer-scale pores with polymeric molecular rulers

Pore-forming properties of proteolytically nicked staphylococcal ⋅-toxin: the ion channel in planar lipid bilayer membranes

ATP hydrolysis-dependent asymmetry of the conformation of CFTR channel pore

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