MODULATION OF ELECTRICAL CONDUCTANCE IN PLANAR LIPID BILAYER MEMBRANES (BLMs)

We studied, by means of alternating current, the electrical properties of planar BLMs made of phosphatidylinositol (PI) or oxidized cholesterol, when incorporating mitochondrial porins (0 – 600 ng/ml). Porin induced an increase of membrane current with time. The maximum porin incorporation rate decreased lowering porin concentration (C). The steady current increased with C. For a same C the incorporation kinetics were faster and higher steady levels were reached in oxidized cholesterol than in PI membranes. The highest values of conductance reached in PI membranes (also with higher C) were always lower than the lowest values obtained with oxidized cholesterol membranes. The applied voltage affected the kinetics and the channel formation. The results show the possibility to modulate the electrical conductance of BLMs by choosing properly the conditions under which to incorporate the protein molecules