Characterization of the transient species generated by the photoexcitation of C-phycocyanin from Spirulina platensis: a laser photolysis and pulse radiolysis study

• Published in: Biochimica et biophysica acta 1999-10, Vol.1472 (1), p.270-278
• Main Authors: Zhang, Su-ping, Qian, Su-ping, Zhao, Jing-quan, Yao, Si-de, Jiang, Li-jin
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - chemistry; C-phycocyanin; Laser photolysis; Oxidation-Reduction; Photolysis; Phycocyanin - chemistry; Pulse Radiolysis; Radical cation; Spirulina; Triplet state
• ISSN: 0304-4165; 0006-3002; 1872-8006
• DOI: 10.1016/S0304-4165(99)00132-4

Nanosecond laser flash photolysis and pulse radiolysis were used to generate and characterize the triplet state and cation radical of C-phycocyanin (C-PC) from Spirulina platensis. The transient absorption spectra of C-PC were measured from direct excitation and acetone sensitization in aqueous solution at room temperature by KrF (248 nm) laser flash photolysis. Laser-induced transient species have been characterized by the method of acetone sensitization and one-electron oxidation. In nitrous oxide-saturated phosphate buffer saline (pH=7.0) of C-PC, the produced intermediates are assigned to the excited triplet state and the radical cation. Using acetone as photosensitizer, the C-PC excited triplet states produced via triplet-triplet energy transfer and the C-PC radical cation from electron transfer reaction were further confirmed. Furthermore, the corresponding kinetic parameters were determined. To our knowledge, the transient absorption spectra of C-PC have been reported for the first time.