Mino H, Kawamori A
Laboratory for Photo-Biology, RIKEN Photodynamics Research Center, The Institute of Physical and Chemical Research, 519-1399 Aoba, Aramaki, Sendai 980-0845, Aoba, Japan.
Biochim Biophys Acta. 2001 Jan 5;1503(1-2):112-22. doi: 10.1016/s0005-2728(00)00229-2.
The parallel polarization electron paramagnetic resonance (EPR) method has been applied to investigate manganese EPR signals of native S1 and S3 states of the water oxidizing complex (WOC) in photosystem (PS) II. The EPR signals in both states were assigned to thermally excited states with S=1, from which zero-field interaction parameters D and E were derived. Three kinds of signals, the doublet signal, the singlet-like signal and g=11-15 signal, were detected in Ca2+-depleted PS II. The g=11-15 signal was observed by parallel and perpendicular modes and assigned to a higher oxidation state beyond S2 in Ca2+-depleted PS II. The singlet-like signal was associated with the g=11-15 signal but not with the Y(Z) (the tyrosine residue 161 of the D1 polypeptide in PS II) radical. The doublet signal was associated with the Y(Z) radical as proved by pulsed electron nuclear double resonance (ENDOR) and ENDOR-induced EPR. The electron transfer mechanism relevant to the role of Y(Z) radical was discussed.
平行极化电子顺磁共振（EPR）方法已被用于研究光系统（PS）II中水分氧化复合物（WOC）的天然S1和S3状态的锰EPR信号。两种状态下的EPR信号都被归因于S = 1的热激发态，并由此推导出零场相互作用参数D和E。在Ca2+耗尽的PS II中检测到三种信号，即双峰信号、类单重态信号和g = 11 - 15信号。g = 11 - 15信号通过平行和垂直模式观察到，并被归因于Ca2+耗尽的PS II中高于S2的更高氧化态。类单重态信号与g = 11 - 15信号相关，但与Y(Z)（PS II中D1多肽的酪氨酸残基161）自由基无关。如脉冲电子核双共振（ENDOR）和ENDOR诱导的EPR所证明，双峰信号与Y(Z)自由基相关。讨论了与Y(Z)自由基作用相关的电子转移机制。
