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Updated: Apr 4, 2026

Anaerobic Protein Purification and Kinetic Analysis via Oxygen Electrode for Studying DesB Dioxygenase Activity and Inhibition
Published on: October 3, 2018
Structural Basis for Oxygen Activation at a Heterodinuclear Manganese/Iron Cofactor
Julia J Griese1, Ramona Kositzki2, Peer Schrapers2
1From the Stockholm Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, SE-106 91 Stockholm, Sweden.
R2-like ligand-binding oxidases (R2lox) with manganese/iron cofactors self-assemble and activate oxygen. Structural analysis reveals cofactor flexibility and potential in vivo metal utilization based on availability.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Two prokaryotic protein groups, class Ic ribonucleotide reductase R2 proteins and R2-like ligand-binding oxidases (R2lox), feature a heterodinuclear manganese/iron cofactor.
- R2lox proteins are prevalent in pathogens and extremophiles.
Purpose of the Study:
- To conduct a detailed structural analysis of R2lox.
- To investigate the nonactivated, reduced, and oxidized resting states of Mn/Fe- and Fe/Fe-bound R2lox, as well as the nonactivated Mn/Mn-bound state.
Main Methods:
- X-ray crystallography
- X-ray absorption spectroscopy
Main Results:
- The active site ligand configuration of R2lox remains consistent across different cofactor compositions (Mn/Fe, Fe/Fe, Mn/Mn).
- Both Mn/Fe and diiron cofactors activate oxygen and catalyze tyrosine-valine ether cross-link formation, unlike the dimanganese cluster.
- Structural insights suggest gated access for oxygen and substrates, controlled by cofactor redox state.
Conclusions:
- Oxygen activation mechanisms are similar for Mn/Fe and Fe/Fe centers in R2lox.
- R2lox proteins may utilize either Mn/Fe or Fe/Fe cofactors in vivo, depending on metal ion availability.
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