Formation of ion channels by a negatively charged analog of gramicidin a

Apell, Hans-Jürgen; Bamberg, Ernst; Alpes, H.; Läuger, P.

doi:10.1007/bf01869403

Cited by 161 publications

(130 citation statements)

References 28 publications

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“…Indeed, the addition of negative charges to the ends of the pore-forming peptide gramicidin increases the current severaifold over the native molecule. Furthermore, the current through the modified pore increases as the ionic strength is lowered, similar to our results described above (Apell et al, 1977).…”

Section: Surface Charges and Permeationsupporting

confidence: 89%

Guanidinium analogues as probes of the squid axon sodium pore. Evidence for internal surface charges.

Smith-Maxwell

Begenisich

1987

The Journal of General Physiology

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A B S T R A C T We have investigated the reduction of steady state sodium channel currents by a monovalent and a divalent guanidinium analogue. The amount of block by the divalent compound at a constant membrane potential was dramatically reduced by an increase in the internal salt concentration. Channel block by the monovalent molecule was a less steep function of salt concentration. These results would be expected if there were negative charges near the sodium pore that produced a local accumulation of the cationic blocking ions. According to this view, the ionic strength dependence of block results from changes in surface potential. The divalent blocker would be expected to be more sensitive to ionic strength owing to its larger valence. Our results can be quantitatively described by a simple ionic double-layer model with an effective surface charge density of about -1 e/250 A s in the vicinity of the pore.

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Section: Surface Charges and Permeationsupporting

confidence: 89%

Guanidinium analogues as probes of the squid axon sodium pore. Evidence for internal surface charges.

Smith-Maxwell

Begenisich

1987

The Journal of General Physiology

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“…At the wide channel entrance charges may be located much more favourably. There they would attract and concentrate ions as has been shown with a pyromellit-derivatized gramicidin channel [24]. Note that charged amino acids are located at the start of helix II.…”

Section: Resultsmentioning

confidence: 82%

The ion channel of the nicotinic acetylcholine receptor is formed by the homologous helices M II of the receptor subunits

1986

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A binding site for the channel-blocking noncompetitive antagonist [3H]triphenylmethylphosphonium ([3H]TPMP') was localized in the cc-, /I-and b-chains of the nicotinic acetylcholine receptor (AChR) from Torpedo marmorata electric tissue. The photolabel was found in homologous positions of the highly conserved sequence helix II, tl 248,j 254, and 6 262. The site of the photoreaction appears to not be affected by the functional state of the receptor. [3H]TPMP+ was found in position 6 262 independent of whether photolabeling was performed with the receptor in its resting, desensitized or antagonist state. A model of the AChR ion channel is proposed, according to which the channel is formed by the five helices II contributed by the five receptor subunits.

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“…16 Consequently, the partition coefficient of gramicidin between a lipid bilayer and water is not known. A partition coefficient of 4.8 × 10 -3 cm was reported for its negatively charged analogue, O-pyromellitylgramicidin, 16 which, however, has a much higher solubility in water.…”

Section: Introductionmentioning

confidence: 99%

Gramicidin Conducting Dimers in Lipid Bilayers Are Stabilized by Single-File Ionic Flux along Them

2007

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Gramicidin D was incorporated in a biomimetic membrane consisting of a lipid bilayer tethered to a mercury electrode via a hydrophilic spacer, and its behavior was investigated in aqueous 0.1 M KCl by potential-step chronocoulometry and electrochemical impedance spectroscopy. The impedance spectra, recorded from 0.1 to 1 × 10 5 Hz over a potential range of 0.7 V, were fitted to a series of RC meshes, which were related to the different substructural elements of the biomimetic membrane. These impedance spectra were compared with those obtained by incorporating valinomycin, under otherwise identical conditions. The potential dependence of the stationary currents reported on bilayer lipid membranes by Bamberg and Läuger (Bamberg, E.; Läuger, P. J. Membrane Biol. 1973, 11, 177-194) as well as those extracted from potential-step chronocoulometric measurements was interpreted by relating the increase in gramicidin dimerization to a progressive increase in single-file K + flux along the dimeric channels. An analogous approach was adopted in explaining the difference between the impedance spectra obtained with gramicidin D and those obtained with valinomycin. It is concluded that gramicidin has a low tendency to form dimers in the absence of ionic flux.

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Formation of ion channels by a negatively charged analog of gramicidin a

Cited by 161 publications

References 28 publications

Guanidinium analogues as probes of the squid axon sodium pore. Evidence for internal surface charges.

Guanidinium analogues as probes of the squid axon sodium pore. Evidence for internal surface charges.

The ion channel of the nicotinic acetylcholine receptor is formed by the homologous helices M II of the receptor subunits

Gramicidin Conducting Dimers in Lipid Bilayers Are Stabilized by Single-File Ionic Flux along Them

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