High-light induced superoxide radical formation in cytochrome b6f complex from Bryopsis corticulans as detected by EPR spectroscopy

The generation of superoxide radical (O2-) in Cyt b6f of Bryopsis corticulans   under high light illumination was studied using electron paramagnetic resonance (EPR) spectroscopy. This could be evidenced by the addition of SOD which specifically reacted with O2-. The generation of O2- was lost in the absence of oxygen and was found to be suppressed in the presence of NaN3 and be scavenged by extraneous antioxidants such as ascorbate, β  -carotene and glutathione which could also scavenged 1O2∗. These results indicated that O2- which produced under high light illumination in Cyt b6f of B. corticulans   might rise from a reaction which 1O2∗ could participated in. Also the photo-protection mechanism to Cyt b6f complex by antioxidants which might contain in thylakoid was speculated.