Boundary potential and tension of planar BLM in the presence of gadolinium measurements in the condition of instant perfusion of the cellстатья
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Статья опубликована в журнале из перечня ВАК
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The changes of membrane tension and boundary potentials were studied with planar BLM made from phosphatidylserine (PS) by instant perfusion of the cell with GdCl3 solutions. The membrane tension was monitored as the BLM capacity changes in response of hydrostatic pressure. Boundary potentials were measured by the method of intramembranous field compensation (IFC). Data on surface potential, charge density and occupancy were obtained from the electrokinetic measurements in liposomes suspension. Dipole compoment of boundary potential was determined as the difference of boundary and surface potentials. It was found the significant increase of boundary potential and membrane tension at the GdCl3 concentration close to zero charge point (10(-5)-10(-6) M) which may correspond to lipid condensation in the bilayer. These effects are absent in BLM made from phosphatidylcholine. Stepwise increase of dipole potential was detected at the threshold tension about 1.5 mN/m. Experiments made at several GdCl3 concentrations show that Gd3+ injection to both compartments of the cell one after another duplicates the value of membrane tension, that indicate the independent input of both BLM monolayers to the effect. At GdCl3 concentrations apart from zero charge point the boundary potential increment corresponds to 20 mV per decade. In frame of GCS model it may be described by Gd3+ binding constants 5 x 10(4) M-1 in the ranges 10(-8)-10(-6) and 10(-5)-10(-1) M, respectively.