[Dark and photo-induced changes in absorption and fluorescence spectra of phycobilisomes in the presence of dithionite].

In order to test the possibility of photochemical participation of phycobilin pigments in photosynthesis, the ability of phycobilisomes for reversible photo-induced redox reactions was studied. The photo-induced fast reversible changes in the absorption and fluorescence spectra of phycobilisomes in the presence of dithionite were found. Simultaneously dithionite induced dark changes revealed by the decrease of the absorption and fluorescence yields. However, the dark and photo-induced changes differ in spectral parameters depending on dithionite concentration. The ability of phycobilisomes to photosensitive redox reactions was demonstrated. A possible nature of dark and photo-induced changes in the absorption and fluorescence spectra of phycobilisomes is discussed.