Photosynthesis Research

, Volume 24, Issue 3, pp 237–243

Studies on the mechanism of photosystem II photoinhibition II. The involvement of toxic oxygen species

  • Michael Richter
  • Wolfgang Rühle
  • Aloysius Wild
Regular Paper

DOI: 10.1007/BF00032311

Cite this article as:
Richter, M., Rühle, W. & Wild, A. Photosynth Res (1990) 24: 237. doi:10.1007/BF00032311

Abstract

In a previous paper it was shown that photoinhibition of reaction centre II of spinach thylakoids was predominantly caused by the degradation of D1-protein. An initial inactivation step at the QB-site was distinguished from its breakdown. The present paper deals with the question as to whether this loss of QB-function is caused by oxygen radical attack. For this purpose the photoinhibition of thylakoids was induced at 20°C in the presence of either superoxide dismutase and catalase or the antioxidants glutathione and ascorbic acid. This resulted in comparable though not total protection of D1-protein, photochemistry and fluorescence from photoinhibition. The combined action of both the enzymatic and the non-enzymatic radical scavenging systems brought about an even more pronounced protective effect against photoinhibition than did either of the two systems singularly at saturating concentrations. The results signify a major contribution of activated oxygen species to the degradation process of D1-protein and the related phenomena of photoinhibition. Thylakoids treated with hydroxyl radicals generated through a Fenton reaction showed a loss of atrazine binding sites, electron transport capacity and variable fluorescence in a similar manner, though not to the same extent, as usually observed following photoinhibitory treatment.

Key words

activated oxygen species D1-protein photoinhibition spinach thylakoids 

Abbreviations

Asc

ascorbate

Fecy

ferricyanide

GSH

reduced glutathione

PQ

plastoquinone

QA

primary quinone acceptor of PS II

QB

secondary quinone acceptor of PS II

SOD

superoxide dismutase

Copyright information

© Kluwer Academic Publishers 1990

Authors and Affiliations

  • Michael Richter
    • 1
  • Wolfgang Rühle
    • 1
  • Aloysius Wild
    • 1
  1. 1.Institute of General Botany of the Johannes Gutenberg UniversityMainzFRG

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