Cytochrome b-559 may function to protect photosystem II from photoinhibition

Lynmarie K. Thompson, Gary W Brudvig

Research output: Contribution to journalArticle

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Abstract

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 6-559 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.

Original languageEnglish
Pages (from-to)6653-6658
Number of pages6
JournalBiochemistry
Volume27
Issue number18
Publication statusPublished - 1988

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Photosystem II Protein Complex
Chlorophyll
Photooxidation
Electrons
Photosynthetic Reaction Center Complex Proteins
Photosynthesis
Electron Spin Resonance Spectroscopy
Cytochromes
cytochrome b559
Oxidants
Paramagnetic resonance
Spectrum Analysis
Monomers
Spectroscopy

ASJC Scopus subject areas

  • Biochemistry

Cite this

Cytochrome b-559 may function to protect photosystem II from photoinhibition. / Thompson, Lynmarie K.; Brudvig, Gary W.

In: Biochemistry, Vol. 27, No. 18, 1988, p. 6653-6658.

Research output: Contribution to journalArticle

Thompson, Lynmarie K. ; Brudvig, Gary W. / Cytochrome b-559 may function to protect photosystem II from photoinhibition. In: Biochemistry. 1988 ; Vol. 27, No. 18. pp. 6653-6658.
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