FAST PHASES OF THE GENERATION OF THE TRANSMEMBRANE ELECTRIC-POTENTIAL IN CHROMATOPHORES OF THE PHOTOSYNTHETIC BACTERIUM ECTOTHIORHODOSPIRA-SHAPOSHNIKOVII

E. shaposnikovii chromatophores were associated with a collodion film and kinetics of generation of the transmembrane electric potential (.DELTA..psi.) were investigated in the chromatophore-collodion film system, using an electrometric technique with a high resolution time (> 200 ns). A generation of .DELTA..psi. (the chromatophore interior positive) following a laser flash was observed, th ekinetics consisting of 3 components of the following half-times; < 200 ns (phase 1); 2-7 .mu.s (phase 2) and 120 .mu.s (phase 3). A redox titration of the kinetic phases was performed. Computer analysis of the results showed that the midpoint potentials (Em) of the phase 1 at pH 7.5 are + 400 mV and -75 mV, whereas those of the phase 2 are + 310 mV and + 35 mV. The comparison of the kinetic and potentiometric characteristics of the .DELTA..psi. generation with analogous characteristics of the electron-transport processes, measured by optical spectroscopy, suggested that phases 1, 2 and 3 are associated with the electron transfer from P-890 to the primary quinone acceptor Qa, from the high-potential cytochrome CH to P-890, and with the reduction of secondary acceptor Qb, respectively. From the amplitude characteristics of the .DELTA..psi. components, a tentative scheme of the intramembrane localization of the electron carriers is presented.