Parallel polarization electron paramagnetic resonance studies of the S-1-state manganese cluster in the photosynthetic oxygen-evolving system

被引:111
作者
Yamauchi, T
Mino, H
Matsukawa, T
Kawamori, A
Ono, T
机构
[1] KWANSEI GAKUIN UNIV,FAC SCI,NISHINOMIYA,HYOGO 662,JAPAN
[2] RIKEN,INST PHYS & CHEM RES,PHOTOSYNTH RES LAB,WAKO,SAITAMA 35101,JAPAN
关键词
D O I
10.1021/bi962791g
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Magnetic properties of the S-1-state manganese cluster in the oxygen-evolving photosystem II were studied by parallel polarization electron paramagnetic resonance spectroscopy. Dark minus light spectra gave rise to a broad S-1-state signal with a g value of about 4.9 [Dexheimer, S, L., Klein, M. P. (1992) J, Am. Chem. Sec. 114, 2821-2826]. Temperature variation of the signal intensity between 1.9 and 10 K observed in PS II with a sucrose buffer indicates that the signal originates from an excited state with a spin S of 1 with separation from the ground state (S = 0) of about 2.5 K. The S-1-state signal was also observed in the sucrose buffer supplemented by 50% glycerol, However, no S-1-state signal was detected by addition of 3% methanol or 30% ethylene glycol in the sucrose buffer, although illumination at 200 K in the presence of these alcohols induced the normal multiline St signal. Furthermore, modification of the Mn cluster by Cl- or Ca2+ depletion from PS II membranes failed to produce a detectable S-1-state signal. A possible magnetic structure of the Mn cluster responsible for the generation of the S-1-state signal is discussed on the basis of these observations.
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页码:7520 / 7526
页数:7
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