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. 1985 Apr;77(4):974–977. doi: 10.1104/pp.77.4.974

Bicarbonate-Reversible and Irreversible Inhibition of Photosystem II by Monovalent Anions 1

Alan Stemler 1,2,2, Judith B Murphy 1,2
PMCID: PMC1064643  PMID: 16664174

Abstract

We tested a number of inhibitory monovalent anions for their primary site of action on photosystem II(PSII) in chloroplasts. We find that the inhibitory effects of F−, HCO2−, NO2−, NO3−, and CH3CO2− are all reversed by addition of a high concentration of HCO3−. This class of anions competitively inhibits H14CO3− binding to PSII. All of those anions tested reduced H14CO3− binding more in the light than in the dark. We conclude that the primary inhibitory site of action of a number of monovalent anions is at the HCO3− binding site(s) on the PSII complex. The carbonic anhydrase inhibitor gold cyanide, and also azide, inhibit PSII but at a site other than the HCO3− binding site. We suggest that the unique ability of HCO3− to reverse the effects of inhibitory anions reflects its singular ability to act as a proton donor/acceptor at the anion binding site. A similar role has been proposed for non-substrate-bound HCO3− on carbonic anhydrase by Yeagle et al. (1975 Proc Natl Acad Sci USA 72: 454-458).

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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