Electrical phenomena associated with release of protons on the surface of bilayer lipid membraneстатьяТезисы
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Дата последнего поиска статьи во внешних источниках: 20 декабря 2019 г.
Аннотация:The changes of the capacitance and electrostatic potential of bilayer lipid membrane (BLM) initiated by fast release of protons on its surface have been studied. The protons were released after photolysis of "Caged-H+" - 2-methoxi-5-nitrosulphate (MNPS) bound on the membrane. This binding was controlled by measuring of the boundary potential (BP) by Inner Field Compensation (IFC) method developed by us earlier (Sokolov and Kuz'min, 1980, Biofizika, 25:170-172) or as the change of zeta-potential of liposomes measured by dynamic light scattering method. The illumination of BLM with bound MNPS by UV light resulted to small increase of its capacitance as well as to appearance of positive charge of its surface detected either as a fast shift of open circuit potential or as a slow BP shift measured by IFC method. The shifts of the membrane capacitance and BP decreased with decrease of pH and with increase of the concentration of buffer in the solution. The effect of buffer on the BP shift was not full and saturated at concentrations above 1 mM. It allows concluding that the BP change is assigned partially to decrease of the amount of the MNPS anions bound on surface of BLM due to their photolysis, partially – to binding of protons with the membrane. The shifts of the membrane capacitance and BP were observed on BLM formed from phospholipids (phosphatidyl choline or phosphatidyl serine) as well as on BLM formed from neutral lipid glycerolmonooleate. The restoration of the capacitance and BP after the light flash took about ten seconds. It indicates that the binding of protons with the membrane leads to forming of a long lived state, in which essential role play water molecules oriented on the membrane surface.