Detection of the photochemical intermediate processes in phycobiliproteins

The delayed luminescence was applied to detect the intermediate processes o f the excited-state decay in the selectively excited phycobiliproteins. Pho sphorescence spectra of the five types of phycobiliproteins, R-PE, CPC, APC , R-PC, PEC were reported in this article. The five phycobiliproteins showe d different phosphorescence yields, the sequence of which was the same as t hat of the singlet oxygen yields. Based on the observation, it can be concl uded that each of the chromophores possesses a characteristic phosphorescen ce emission. The delayed luminescence spectra of APC at different aggregati on states (trimer, monomer and denatured APC) are researched. The lower agg regation APC showed less phosphorescence because of relative loose structur es and less interaction with the surrounding proteins, while the denatured APC showed delayed fluorescence instead of phosphorescence because of tripl et-triplet annihilation.