Stockholm university

Friederike AllgöwerPhD student

About me

PhD Student of Prof. Ville Kaila at the Department of Biochemistry and Biophysics, Stockholm University

Office: A571a

Expected PhD graduation date: April 2024 
2017-2019: M.Sc. in Physical and Theoretical Chemistry at TU Munich, Germany
2014-2017: B.Sc. in Chemistry at University of Stuttgart, Germany


* Bioinformatics, MSc Level
* Structural Biochemistry, MSc Level
* Experimental Chemical Methods, BSc Level
* Molecular Structure and Statistical Thermodynamics, BSc Level
* Mathematical Methods in Chemistry, BSc Level


Mechanisms of Proton-Coupled Electron Transfer in Respiratory and Photosynthetic Energy Conversion


A selection from Stockholm University publication database

  • Bicarbonate-controlled reduction of oxygen by the QA semiquinone in Photosystem II in membranes

    2022. Andrea Fantuzzi (et al.). Proceedings of the National Academy of Sciences of the United States of America 119 (6)


    Photosystem II (PSII), the water/plastoquinone photo-oxidoreductase, plays a key energy input role in the biosphere. , the reduced semiquinone form of the nonexchangeable quinone, is often considered capable of a side reaction with O2, forming superoxide, but this reaction has not yet been demonstrated experimentally. Here, using chlorophyll fluorescence in plant PSII membranes, we show that O2 does oxidize at physiological O2 concentrations with a t1/2 of 10 s. Superoxide is formed stoichiometrically, and the reaction kinetics are controlled by the accessibility of O2 to a binding site near , with an apparent dissociation constant of 70 ± 20 µM. Unexpectedly, could only reduce O2 when bicarbonate was absent from its binding site on the nonheme iron (Fe2+) and the addition of bicarbonate or formate blocked the O2-dependant decay of . These results, together with molecular dynamics simulations and hybrid quantum mechanics/molecular mechanics calculations, indicate that electron transfer from to O2 occurs when the O2 is bound to the empty bicarbonate site on Fe2+. A protective role for bicarbonate in PSII was recently reported, involving long-lived triggering bicarbonate dissociation from Fe2+ [Brinkert et al., Proc. Natl. Acad. Sci. U.S.A. 113, 12144–12149 (2016)]. The present findings extend this mechanism by showing that bicarbonate release allows O2 to bind to Fe2+ and to oxidize . This could be beneficial by oxidizing and by producing superoxide, a chemical signal for the overreduced state of the electron transfer chain.

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  • Molecular Principles of Redox-Coupled Protonation Dynamics in Photosystem II

    2022. Friederike Allgöwer (et al.). Journal of the American Chemical Society 144 (16), 7171-7180


    Photosystem II (PSII) catalyzes light-driven water oxidization, releasing O2 into the atmosphere and transferring the electrons for the synthesis of biomass. However, despite decades of structural and functional studies, the water oxidation mechanism of PSII has remained puzzling and a major challenge for modern chemical research. Here, we show that PSII catalyzes redox-triggered proton transfer between its oxygen-evolving Mn4O5Ca cluster and a nearby cluster of conserved buried ion-pairs, which are connected to the bulk solvent via a proton pathway. By using multi-scale quantum and classical simulations, we find that oxidation of a redox-active Tyrz (Tyr161) lowers the reaction barrier for the water-mediated proton transfer from a Ca2+-bound water molecule (W3) to Asp61 via conformational changes in a nearby ion-pair (Asp61/Lys317). Deprotonation of this W3 substrate water triggers its migration toward Mn1 to a position identified in recent X-ray free-electron laser (XFEL) experiments [Ibrahim et al. Proc. Natl. Acad. Sci. USA 2020, 117, 12,624–12,635]. Further oxidation of the Mn4O5Ca cluster lowers the proton transfer barrier through the water ligand sphere of the Mn4O5Ca cluster to Asp61 via a similar ion-pair dissociation process, while the resulting Mn-bound oxo/oxyl species leads to O2 formation by a radical coupling mechanism. The proposed redox-coupled protonation mechanism shows a striking resemblance to functional motifs in other enzymes involved in biological energy conversion, with an interplay between hydration changes, ion-pair dynamics, and electric fields that modulate the catalytic barriers. 

    Read more about Molecular Principles of Redox-Coupled Protonation Dynamics in Photosystem II

Show all publications by Friederike Allgöwer at Stockholm University