ABSTRACT
In reaction centres of photosynthetic membranes of R, rubrum the efficiency of redox interactions of the photoreduced primary electron acceptor with secondary acceptors and photooxidized bacteriochlorophyll has a marked and reversible dependence on temperature over the range from -20 degrees to -80 degrees. Similar temperature dependences were observed for correlation times of the rotational diffusion of a spin probe bound to the hydrophobic region of the membrane and of a spin label bound to SH-groups of the protein constituent of the membrane, as well as for characteristics of resonance absorption of the Mössbauer probe (57Fe), embedded in the membrane by biosynthesis. Using the same indicators of intramolecular mobility, a correlation has been observed between photoactivity and structure of the membrane in experiments involving hydratation changes of samples. The data suggest the existence of a close interrelationship between the conformational mobility of the constituents of the photosynthetic membrane and their specific reaction capacity.
