塑料醌
光系统II
P680页
化学
电子转移
结晶学
700页
氧化还原酶
二聚体
光系统I
光化学
光合作用
类囊体
叶绿体
生物化学
基因
有机化学
酶
出处
期刊:Quarterly Reviews of Biophysics
[Cambridge University Press]
日期:2003-01-27
卷期号:36 (1): 71-89
被引量:238
标识
DOI:10.1017/s0033583502003839
摘要
Photosystem II (PS II) is a multisubunit membrane protein complex, which uses light energy to oxidize water and reduce plastoquinone. High-resolution electron cryomicroscopy and X-ray crystallography are revealing the structure of this important molecular machine. Both approaches have contributed to our understanding of the organization of the transmembrane helices of higher plant and cyanobacterial PS II and both indicate that PS II normally functions as a dimer. However the high-resolution electron density maps derived from X-ray crystallography currently at 3.7/3.8 A, have allowed assignments to be made to the redox active cofactors involved in the light-driven water-plastoquinone oxidoreductase activity and to the chlorophyll molecules that absorb and transfer energy to the reaction centre. In particular the X-ray work has identified density that can accommodate the four manganese atoms which catalyse the water-oxidation process. The Mn cluster is located at the lumenal surface of the DI protein and approximately 7 A from the redox active tyrosine residue (YZ) which acts an electron/proton transfer link to the primary oxidant P680.+. The lower resolution electron microscopy studies, however, are providing structural models of larger PS II supercomplexes that are ideal frameworks in which to incorporate the X-ray derived structures.
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