In phosphatidylserine membranes the decrease in the conductance of the gramicidin A single channel caused by calcium is attributed to a reduction of surface potential and to a direct blocking of the pore (Apell et al. 1979). The aim of this paper is to make a quantitative evaluation of these two effects. We recorded the conductance of gramicidin single channels in 100 mM KCl in the presence of different amounts of CaCl2, MgCl2 or TEACl. The ionic activities at the channel mouth were calculated using the Gouy-Chapman-Stern theory. Our experiments showed that even when the K+ activity at the channel mouth was estimated to be the same, the single channel conductance was lower if divalent cations were present. This effect is attributed to a blocking action of these ions.

Effects of calcium on the gramicidin A single channel in phosphatidylserine membranes: screening and blocking / Gambale, F.; Menini, Anna; Rauch, G.. - In: EUROPEAN BIOPHYSICS JOURNAL WITH BIOPHYSICS LETTERS. - ISSN 0175-7571. - 14:6(1987), pp. 369-374. [10.1007/BF00262322]

Effects of calcium on the gramicidin A single channel in phosphatidylserine membranes: screening and blocking.

Menini, Anna;
1987-01-01

Abstract

In phosphatidylserine membranes the decrease in the conductance of the gramicidin A single channel caused by calcium is attributed to a reduction of surface potential and to a direct blocking of the pore (Apell et al. 1979). The aim of this paper is to make a quantitative evaluation of these two effects. We recorded the conductance of gramicidin single channels in 100 mM KCl in the presence of different amounts of CaCl2, MgCl2 or TEACl. The ionic activities at the channel mouth were calculated using the Gouy-Chapman-Stern theory. Our experiments showed that even when the K+ activity at the channel mouth was estimated to be the same, the single channel conductance was lower if divalent cations were present. This effect is attributed to a blocking action of these ions.
1987
14
6
369
374
Gambale, F.; Menini, Anna; Rauch, G.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/17145
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