Quantification of bound bicarbonate in photosystem II#
2018 (English)In: Photosynthetica (Praha), ISSN 0300-3604, E-ISSN 1573-9058, Vol. 56, no 1, p. 210-216Article in journal (Refereed) Published
Abstract [en]
In this study, we presented a new approach for quantification of bicarbonate (HCO3-) molecules bound to PSII. Our method, which is based on a combination of membrane-inlet mass spectrometry (MIMS) and O-18-labelling, excludes the possibility of "non-accounted" HCO3- by avoiding (1) the employment of formate for removal of HCO3- from PSII, and (2) the extremely low concentrations of HCO3-/CO2 during online MIMS measurements. By equilibration of PSII sample to ambient CO2 concentration of dissolved CO2/HCO3-, the method ensures that all physiological binding sites are saturated before analysis. With this approach, we determined that in spinach PSII membrane fragments 1.1 +/- 0.1 HCO3- are bound per PSII reaction center, while none was bound to isolated PsbO protein. Our present results confirmed that PSII binds one HCO3- molecule as ligand to the non-heme iron of PSII, while unbound HCO3- optimizes the water-splitting reactions by acting as a mobile proton shuttle.
Place, publisher, year, edition, pages
2018. Vol. 56, no 1, p. 210-216
Keywords [en]
hydrogen carbonate, inorganic carbon, mass spectrometry, Mn-stabilizing protein, non-heme iron, ygen-evolving complex
National Category
Biophysics
Identifiers
URN: urn:nbn:se:umu:diva-138611DOI: 10.1007/s11099-017-0758-4ISI: 000430309200019OAI: oai:DiVA.org:umu-138611DiVA, id: diva2:1854
Funder
Knut and Alice Wallenberg FoundationSwedish Research Council, 2016-051832018-06-052018-06-052018-06-05Bibliographically approved