Proximity of the manganese cluster of photosystem II to the redox-active tyrosine YZ.
Proximity of the manganese cluster of photosystem II to the redox-active tyrosine YZ.
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光系统 II 的锰簇与氧化还原活性酪氨酸 YZ 的接近度。
DOI：
10.1073/pnas.92.21.9545
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发表时间：
1995
影响因子：
11.1
通讯作者：
Britt,RD
中科院分区：
文献类型：
--
作者：
GilchristJr,ML;Ball,JA;Randall,DW;Britt,RD
电子自旋回波电子-核双共振（ESE-ENDOR）实验上进行的广泛的自由基电子顺磁共振（EPR）的光系统II颗粒中观察到的Ca 2+耗尽的信号表明，这个信号来自氧化还原活性酪氨酸YZ。酪氨酸EPR信号宽度增加相对于在锰耗尽的制备中观察到的，由于光系统II锰簇和酪氨酸自由基之间的磁相互作用。锰簇相对于与锰相关的酪氨酸YZ和YD不对称地定位。YZ酪氨酸和锰簇之间的距离估计约为4.5 A。由于Mn簇和氧化还原活性酪氨酸YZ的这种紧密接近，我们建议，这种酪氨酸从结合到Mn簇的底物水中提取质子。
Electron spin echo electron-nuclear double resonance (ESE-ENDOR) experiments performed on a broad radical electron paramagnetic resonance (EPR) signal observed in photosystem II particles depleted of Ca2+ indicate that this signal arises from the redox-active tyrosine YZ. The tyrosine EPR signal width is increased relative to that observed in a manganese-depleted preparation due to a magnetic interaction between the photosystem II manganese cluster and the tyrosine radical. The manganese cluster is located asymmetrically with respect to the symmetry-related tyrosines YZ and YD. The distance between the YZ tyrosine and the manganese cluster is estimated to be approximately 4.5 A. Due to this close proximity of the Mn cluster and the redox-active tyrosine YZ, we propose that this tyrosine abstracts protons from substrate water bound to the Mn cluster.