[Model of the selective calcium channel of characean algae]. / Model' selektivnogo kal'tsievogo kanala kletok kharovoi vodorosli.

The present work was intended to further investigate the selective filter of calcium channel on both a cell membrane and reconstructed channels. For the studies on cell membranes, an inhibitor of chloride channels was chosen (ethacrynic acid) to pass currents only through the calcium channels. On both the cells and reconstructed channels, permeability of ions of different crystal radii and valencies was investigated. The obtained results suggest that the channel represents a wide water pore with a diameter larger than 8 A into which ions go together with the nearest water shell. The values of the maximal currents are given by electrostatic interaction of the ions with the anion center of the channel. A phenomenological two-barrier model of the channel is given which describes the movement of all the ions studied.

[Chemical composition of calcium channels of characean algal cells]. / O khimicheskom sostave kal'tsievykh kanalov kletok kharovoi vodorosli.

The present study was performed to determine the chemical composition and molecular weight of channel-forming complex by fractioning the cell homogenate supernatant by different means (chromatography, gel-electrophoresis, using dissociating and denaturating agents). Availability of the channel-forming complexes in individual fractions is judged from reconstruction of channels in BLM. The Ca-channels reconstructed in BLM are formed by molecules of a protein nature (presumably, peptides). Their molecular weight is no more than 20000 (presumably, 5000). A high stability of spacial organization of channel forming molecules was observed. The channels--subunits aggregate without any change in properties of the selective filter. The thermodynamically preferred agagregates have conductivity of 200 pmho in 0.1 M KCl and seem to consist of 80 channels--subunits which are switched off and on all together.