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Sang M, Ma F, Xie J, Chen XB, Wang KB, Qin XC, Wang WD, Zhao JQ, Li LB, Zhang JP, Kuang TY: High-light induced singlet oxygen formation in cytochrome b (6) f complex from Bryopsis corticulans as detected by EPR spectroscopy. Biophys Chem. 2010 Jan;146(1):7-12. Epub 2009 Oct 6.
Electron paramagnetic resonance (EPR) spectroscopy was used to detect the light-induced formation of singlet oxygen ((1) O (2)*) in the intact and the Rieske-depleted cytochrome b (6) f complexes (Cyt b (6) f) from Bryopsis corticulans, as well as in the isolated Rieske Fe-S protein. It is shown that, under white-light illumination and aerobic conditions, chlorophyll a (Chl a) bound in the intact Cyt b (6) f can be bleached by light-induced (1) O (2)*, and that the (1) O (2)* production can be promoted by D (2) O or scavenged by extraneous antioxidants such as l-histidine, ascorbate, beta-carotene and glutathione. Under similar experimental conditions, (1) O (2)* was also detected in the Rieske-depleted Cyt b (6) f complex, but not in the isolated Rieske Fe-S protein. The results prove that Chl a cofactor, rather than Rieske Fe-S protein, is the specific site of (1) O (2)* formation, a conclusion which draws further support from the generation of (1) O (2)* with selective excitation of Chl a using monocolor red light. |
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