Quantification of bound bicarbonate in photosystem II. Tikhonov, K., Shevela, D., Klimov, V. V., & Messinger, J. Photosynthetica, 56(1):210–216, March, 2018.
Quantification of bound bicarbonate in photosystem II [link]Paper  doi  abstract   bibtex   
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 18O-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.
@article{tikhonov_quantification_2018,
	title = {Quantification of bound bicarbonate in photosystem {II}},
	volume = {56},
	issn = {1573-9058},
	url = {https://doi.org/10.1007/s11099-017-0758-4},
	doi = {10.1007/s11099-017-0758-4},
	abstract = {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 18O-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.},
	language = {en},
	number = {1},
	urldate = {2024-12-10},
	journal = {Photosynthetica},
	author = {Tikhonov, K. and Shevela, D. and Klimov, V. V. and Messinger, J.},
	month = mar,
	year = {2018},
	keywords = {Mn-stabilizing protein, hydrogen carbonate, inorganic carbon, mass spectrometry, non-heme iron, oxygen-evolving complex},
	pages = {210--216},
}

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