High-light induced singlet oxygen formation in cytochrome b(6)f complex from Bryopsis corticulans as detected by EPR spectroscopy.
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.
Institute of Botany, Chinese Academy of Sciences, Beijing, PR China.
Min
M
Sang
Fei
F
Ma
Jie
J
Xie
Xiao-Bo
XB
Chen
Ke-Bin
KB
Wang
Xiao-Chun
XC
Qin
Wen-Da
WD
Wang
Jing-Quan
JQ
Zhao
Liang-Bi
LB
Li
Jian-Ping
JP
Zhang
Ting-Yun
TY
Kuang
D000975:Antioxidants / Q000737:chemistry; D001205:Ascorbic Acid / Q000737:chemistry; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D000460:Chlorophyta / Q000378:metabolism; D045346:Cytochrome b6f Complex / Q000737:chemistry* / Q000528:radiation effects*; D004578:Electron Spin Resonance Spectroscopy; D014450:Electron Transport Complex III / Q000378:metabolism; D005978:Glutathione / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D008027:Light; D026082:Singlet Oxygen / Q000378:metabolism* / Q000528:radiation effects; D019207:beta Carotene / Q000737:chemistry
D000975:Antioxidants; C037989:Rieske iron-sulfur protein; D019207:beta Carotene; D002734:Chlorophyll; D026082:Singlet Oxygen; D006639:Histidine; D045346:Cytochrome b6f Complex; D014450:Electron Transport Complex III; D005978:Glutathione; D001205:Ascorbic Acid; D000077194:Chlorophyll A