Journal Article

Weak Light-Induced Oxygen Consumption Observed during Photoreactivation Is Coupled to the Recovery of Oxygen Evolving Activity

Masumi Ebina and Takashi Yamashita

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 37, issue 8, pages 1059-1065
Published in print December 1996 | ISSN: 0032-0781
e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/oxfordjournals.pcp.a029054
Weak Light-Induced Oxygen Consumption Observed during Photoreactivation Is Coupled to the Recovery of Oxygen Evolving Activity

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During photoreactivation of the O2-evolving center in Tris-inactivated/Mn-depleted thylakoids, a slow O2-consumption occurred. This O2-consumption became detectable when the O2-evolving activity of thylakoids was inactivated by Tris-treatment and decreased as photoreactivation proceeded. The O2-consumption and photoreactivation similarly required Mn2+ at μM levels in addition to PSII electron donors and shared severa common characteristics. Stimulation of O2-consumption and photoreactivation by these cofactors were always accompanied by enhancement in chlorophyll fluorescence induction, suggesting the involvement of a Mehler-type reaction in photoreactivation. Although the electron transport due to this O2-consumption was rapid enough to oxidize 4 Mn2+ ions to reconstitute the tetranuclear Mn-cluster in each O2-evolving center in a few seconds, actual recovery of O2-evolving activity occurred more slowly in a few minutes. It was inferred that photoreactivation in Tris-inactivated thylakoids is not a simple photooxidation of Mn22+ but involves more complicated processes which are coupled to the Mehlertype electron transport from PSII to oxygen via PSI.

Keywords: Effect of weak light; Effect of Mn2+; O2; consumption; O2evolution; Photoreactivation; Trisinactivated thylakoids

Journal Article.  0 words. 

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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