Pulse radiolysis at planar lipid membranes doped with ion carriers or pore formers

Stark, G.; Strässle, Manuel; Wilhelm, Martin

doi:10.1016/0005-2736(84)90179-2

Cited by 13 publications

(4 citation statements)

References 8 publications

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“…The shape of the dose-response curve observed after application of a series of pulses of 14 MeV electrons could be approximated by an exponential function (Stark et al 1984) . A more careful inspection of the inactivation curve based on continuous irradiation with 220 kV X-rays ( The membranes were formed from dioleoyllecithin .…”

Section: Resultsmentioning

confidence: 99%

“…The main advantage of the planar lipid membrane system, namely the easy access to the electrical properties of the membrane, has not been utilized for the study of radiation effects so far . We have shown recently that the conductance of planar (black) lipid membranes doped with ion carriers or pore formers may change by many orders of magnitude on irradiation with 14 MeV electrons (Stark et al 1984) . We have further shown that the method of pulse radiolysis, so far confined to macroscopic solutions, may be applied to planar lipid membranes, too .…”

Section: Introductionmentioning

confidence: 99%

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Effects of Ionizing Radiation on Artificial (Planar) Lipid Membranes. I. Radiation Inactivation of the Ion Channel Gramicidin A

Strässle

Stark²,

Wilhelm

1987

International Journal of Radiation Biology and Related Studies

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The ion channel formed by the pentadecapeptide gramicidin A in planar lipid membranes is extremely sensitive to ionizing radiation. The membrane conductance may drop by several orders of magnitude under appropriate experimental conditions (low pH and presence of oxygen). The radiation sensitivity is strongly reduced for gramicidin M-. This analogue has the four tryptophan residues replaced by phenylalanines. Experiments performed in the presence of various radical scavengers suggest that the inactivation of the channel is due to a combined action of OH and of HO2 radicals at the tryptophan residues. The shape of the inactivation curves following continuous radiolysis or pulse radiolysis were found to be in fair agreement with a simple model which assumes that the damage of a single tryptophan residue is sufficient for channel inactivation. The conductance of inactivated channels could not be resolved within the experimental accuracy. This is contrary to photolysis of gramicidin channels found by Busath and Waldbilling (1983), where a broad distribution of low conductance states was observed. The inactivation by radiolysis seems to represent an 'all-or-none-process' of the channel conductance.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Ionizing Radiation on Artificial (Planar) Lipid Membranes. I. Radiation Inactivation of the Ion Channel Gramicidin A

Strässle

Stark²,

Wilhelm

1987

International Journal of Radiation Biology and Related Studies

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“…The length of the radical chain is limited by the bimolecular termination reaction. Its importance increases with the second power of the radical concentration LOO, which depends linearly on the dose rate, D. The reaction chain may be analyzed by introducing the kinetic chain length, v, defined by number of 02 molecules consumed (7) v = initiating radical Xv is equal to the number of lipid hydroperoxides formed per initiating radical. The formal analysis ofthe reaction scheme yields (assuming v > 1, see (5) or (35)): oLH =(ab)1/2' (8) with o = kp/(2k,)112, LH = concentration of the lipid, aD = formation rate of radicals X-.…”

Section: Discussionmentioning

confidence: 99%

“…Inactivation may result from a chemical reaction with free radicals generated by water radiolysis. The membrane conductance induced by gramicidin A is reduced by many orders of magnitude by a reaction of OH and of HO; radicals with the tryptophan residues of the peptide (7)(8)(9). The hydroxyl radical OH' and the perhydroxyl radical Ho2 (as well as other oxygen radicals) are well known for their deleterious cellular effects and have been discussed in the context with a variety of diseases ( 10).…”

Section: Introductionmentioning

confidence: 99%

Inactivation by ionizing radiation of ion channels formed by polyene antibiotics amphotericin B and nystatin in lipid membranes: an inverse dose-rate behavior

Barth¹,

Stark²,

Wilhelm³

1993

Biophysical Journal

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The phenomena reported are part of a study about the effects of ionizing radiation on membrane transport. We found that the conductance of lipid membranes in the presence of the polyene-antibiotics nystatin or amphotericin B is reduced to virtually zero following irradiation. Ion channels formed by these substances seem to represent extremely sensitive structures being inactivated by radiation doses in the range of a few Centigray (1 cGy = 1 rad) at sufficiently small dose rates. Inactivation shows a so-called inverse dose-rate behavior, i.e., at constant radiation dose the effect increases with decreasing dose rate. Similar to radiation-induced lipid peroxidation the phenomenon may be understood on the basis of a radical chain mechanism initiated by free radicals of water radiolysis. The process--via peroxidation of the polyene part of the molecules--is suggested to modify the hydrophobic exterior and to destabilize the barrel-like structure of the ion channels.

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NMR analysis of the ultraviolet photolytic behavior of several tryptophan-rich growth hormone releasing peptides

McKim¹,

Hinton²,

Deghenghi³

1997

Biospectroscopy

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Pulse radiolysis at planar lipid membranes doped with ion carriers or pore formers

Cited by 13 publications

References 8 publications

Effects of Ionizing Radiation on Artificial (Planar) Lipid Membranes. I. Radiation Inactivation of the Ion Channel Gramicidin A

Effects of Ionizing Radiation on Artificial (Planar) Lipid Membranes. I. Radiation Inactivation of the Ion Channel Gramicidin A

Inactivation by ionizing radiation of ion channels formed by polyene antibiotics amphotericin B and nystatin in lipid membranes: an inverse dose-rate behavior

NMR analysis of the ultraviolet photolytic behavior of several tryptophan-rich growth hormone releasing peptides

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