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The diameter of water pores formed by colicin Ia in planar lipid bilayers
O V Krasilnikov1, L N Yuldasheva, R A Nogueira
1Laboratory of Molecular Physiology, Institute of Physiology and Biophysics, Tashkent, Uzbekistan.
Abstract:
The effective size of colicin Ia channel was tested by a recently described method (FEMS, Microbiology and Immunology (1992). 105: 93-100) in which the nonelectrolyte molecules with different hydrodynamic diameters (0.52 to 5.0 nm) were used as molecular tools. We have shown that despite low conductance (55-105 pS at 1.5 M KCl, pH 7.0) the ion channels formed by colicin Ia have a fairly large water pore diameter equal to 1.66-1.88 nm. The results are discussed in terms of an energetic barrier for ions passing into the channel lumen.