[Spectral position of the principal absorption band of pigment complex P870 and the kinetics of photo-induced oxidoreductions in the reaction centers and chromatophores of purple bacteria with preparations at different temperatures and having different degrees of hydration]

Abstract

In isolated photosynthetic reaction centres of Rps. spheroides and chromatophores R. rubrum the spectral position of the longest wavelength absorption band of P870, effectiveness of electron removal from the photochemical pair (P870 -- primary electron acceptor, A1) and the rate constant for recombination of photooxidized P870 with photoreduced A1 undergo marked and fully reversible changes over the temperature interval from +20 to -70 degrees. Dehydration of the samples has the effect similar to that induced by temperature lowering. The data suggest that the spectral position of the main maximum of pigment complex P870 absorption band may be regarded as a sensitive inner probe of the structure-functional state of the investigated preparations.