A STUDY OF ION CHANNELS IN A PHOTOSYNTHET IC MEMBRANE OF PURPLE BACTERIA

The present work concerns the mechanism of ion conductivity of photosy nthetic membranes. It is shown that the reconstitution of vesicles of photosynthetic membranes (chromatophors) of purple bacteria Rhodospiri llum rubrum into planar bilayer lipid membrane leads to fluctuations o f currents showing the existence of channels with predominant amplitud e of 230 pS in the presence of 100 mM KCl. Measurements under the cond itions of KCl gradient show that this channel is cation selective (P(K )/P(Cl) = 7.2). Voltage inactivation of the channel is demonstrated wh ich is prevented by the treatment with trypsin.