Effect of cationic antiseptics on fluorescent characteristics and electron transfer in cyanobacterial photosystem I complexes.

In this study, the effects of cationic antiseptics such as chlorhexidine, picloxidine, miramistin, and octenidine at concentrations up to 150 µM on fluorescence spectra and its lifetimes, as well as on light-induced electron transfer in protein-pigment complexes of photosystem I (PSI) isolated from cyanobacterium Synechocystis sp. PCC 6803 have been studied. In doing so, octenidine turned out to be the most "effective" in terms of its influence on the spectral and functional characteristics of PSI complexes. It has been shown that the rate of energy migration from short-wavelength forms of light-harvesting chlorophyll to long-wavelength ones slows down upon addition of octenidine to the PSI suspension. After photo-separation of charges between the primary electron donor P₇₀₀ and the terminal iron-sulfur center(s) F_A/F_B, the rate of forward electron transfer from (F_A/F_B)^- to the external medium slows down while the rate of charge recombination between reduced F_A/F_B^- and photooxidized P₇₀₀⁺ increases. The paper considers the possible causes of the observed action of the antiseptic.