Imperial College London

Professor Bill Rutherford FRS

Faculty of Natural SciencesDepartment of Life Sciences

Chair in Biochemistry of Solar Energy



+44 (0)20 7594 5329a.rutherford Website




702Sir Ernst Chain BuildingSouth Kensington Campus






BibTex format

author = {Rutherford, AW and Fantuzzi, A and Brinkert, K and De, Causmaecker and Kreiger-Liszkay, A},
doi = {10.1073/pnas.1608862113},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
pages = {12144--12149},
title = {Bicarbonate-induced redox tuning in Photosystem II for regulation and protection},
url = {},
volume = {113},
year = {2016}

RIS format (EndNote, RefMan)

AB - The midpoint potential (Em) of QA/Q−AQA/QA−•, the one-electron acceptor quinone of Photosystem II (PSII), provides the thermodynamic reference for calibrating PSII bioenergetics. Uncertainty exists in the literature, with two values differing by ∼80 mV. Here, we have resolved this discrepancy by using spectroelectrochemistry on plant PSII-enriched membranes. Removal of bicarbonate (HCO3−) shifts the Em from ∼−145 mV to −70 mV. The higher values reported earlier are attributed to the loss of HCO3− during the titrations (pH 6.5, stirred under argon gassing). These findings mean that HCO3− binds less strongly when QA−• is present. Light-induced QA−• formation triggered HCO3− loss as manifest by the slowed electron transfer and the upshift in the Em of QA. HCO3−-depleted PSII also showed diminished light-induced 1O2 formation. This finding is consistent with a model in which the increase in the Em of QA/Q−AQA/QA−• promotes safe, direct P+Q−AP+•QA−• charge recombination at the expense of the damaging back-reaction route that involves chlorophyll triplet-mediated 1O2 formation [Johnson GN, et al. (1995) Biochim Biophys Acta 1229:202–207]. These findings provide a redox tuning mechanism, in which the interdependence of the redox state of QA and the binding by HCO3− regulates and protects PSII. The potential for a sink (CO2) to source (PSII) feedback mechanism is discussed.
AU - Rutherford,AW
AU - Fantuzzi,A
AU - Brinkert,K
AU - De,Causmaecker
AU - Kreiger-Liszkay,A
DO - 10.1073/pnas.1608862113
EP - 12149
PY - 2016///
SN - 1091-6490
SP - 12144
TI - Bicarbonate-induced redox tuning in Photosystem II for regulation and protection
T2 - Proceedings of the National Academy of Sciences of the United States of America
UR -
UR -
VL - 113
ER -