Back to Search
Start Over
Bicarbonate-Mediated CO2 Formation on Both Sides of Photosystem II
- Source :
- Biochemistry
- Publication Year :
- 2020
- Publisher :
- Uppsala universitet, Molekylär biomimetik, 2020.
-
Abstract
- The effect of bicarbonate (HCO3-) on photosystem II (PSII) activity was discovered in the 1950s, but only recently have its molecular mechanisms begun to be clarified. Two chemical mechanisms have been proposed. One is for the electron-donor side, in which mobile HCO3- enhances and possibly regulates water oxidation by acting as proton acceptor, after which it dissociates into CO2 and H2O. The other is for the electron-acceptor side, in which (i) reduction of the Q(A) quinone leads to the release of HCO(3)(- )from its binding site on the non-heme iron and (ii) the E-m potential of the Q(A)/Q(.-) couple increases when HCO3- dissociates. This suggested a protective/regulatory role of HCO3- as it is known that increasing the E-m of Q(A) decreases the extent of back-reaction-associated photodamage. Here we demonstrate, using plant thylakoids, that time-resolved membrane-inlet mass spectrometry together with C-13 isotope labeling of HCO3- allows donor- and acceptor-side formation of CO2 by PSII to be demonstrated and distinguished, which opens the door for future studies of the importance of both mechanisms under in vivo conditions.
- Subjects :
- Photosystem II
Bicarbonate
Biochemistry and Molecular Biology
Biophysics
Photosystem II Protein Complex
Carbon Dioxide
Thylakoids
Biochemistry
Article
Biofysik
Electron Transport
Bicarbonates
chemistry.chemical_compound
chemistry
Spinacia oleracea
Oxidation-Reduction
Biokemi och molekylärbiologi
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Biochemistry
- Accession number :
- edsair.doi.dedup.....b8d3e7b0b8524824b2d9bb785834fb20