Cytochrome b-559 may function to protect photosystem II from photoinhibition.
Cytochrome b-559 may function to protect photosystem II from photoinhibition.
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DOI：
10.1021/bi00418a002
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发表时间：
1988-09
期刊：
影响因子：
2.9
通讯作者：
Lynmarie K. Thompson;G. Brudvig
中科院分区：
文献类型：
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作者：
Lynmarie K. Thompson;G. Brudvig
虽然细胞色素B-559是光系统II复合物（PSII）的组成部分，但其功能尚不清楚。由于细胞色素B-559已被证明是光氧化和光还原的PSII，几个建议之一是，它介导的PSII周围的循环电子转移，可能作为一种保护机制。我们已经使用电子顺磁共振光谱研究光系统II中细胞色素B-559的光氧化途径，并表明它通过叶绿素的光氧化进行。我们建议，叶绿素的光氧化是PSII光抑制的第一步。PSII对光抑制的独特敏感性可能是由于它是光合作用中唯一的反应中心，其产生具有足够高的还原电位以氧化叶绿素的氧化剂。我们认为细胞色素B-559的功能是通过介导循环电子转移来再还原光氧化的叶绿素，保护PSII免受光抑制。我们还认为，叶绿素（S），这是敏感的光氧化是类似的单体叶绿素中发现的细菌光合反应中心复合体。
Although cytochrome b-559 is an integral component of the photosystem II complex (PSII), its function is unknown. Because cytochrome b-559 has been shown to be both photooxidized and photoreduced in PSII, one of several proposals is that it mediates cyclic electron transfer around PSII, possibly as a protective mechanism. We have used electron paramagnetic resonance spectroscopy to investigate the pathway of photooxidation of cytochrome b-559 in PSII and have shown that it proceeds via photooxidation of chlorophyll. We propose that this photooxidation of chlorophyll is the first step in the photoinhibition of PSII. The unique susceptibility of PSII to photoinhibition is probably due to the fact that it is the only reaction center in photosynthesis which generates an oxidant with a reduction potential high enough to oxidize chlorophyll. We propose that the function of cytochrome b-559 is to mediate cyclic electron transfer to rereduce photooxidized chlorophyll and protect PSII from photoinhibition. We also suggest that the chlorophyll(s) which are susceptible to photooxidation are analogous to the monomer chlorophylls found in the bacterial photosynthetic reaction center complex.