ArticleBiochemistry2013
Triplet state of the semiquinone-Rieske cluster as an intermediate of electronic bifurcation catalyzed by cytochrome bc1.
Article in Biochemistry, 2013. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 22 papers.
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Who cites it
22 citing papers in PubMed, 47 citations in OpenAlex.
- Recent insights into the molecular mechanism of ubiquinol oxidation by cytochrome bcFEBS open bio · 2026Review
- Photocatalytic Solar Hydrogen Peroxide Production on Donor+Acceptor Linear Polymer Semiconductor Powders Reconfigurable by H-Bonding and π-Stacking Interactions.Angewandte Chemie (International ed. in English) · 2026Article
- Article
- Intricacies in iron-sulfur cluster function and biogenesis: functional versatility, sulfur sources, and enzyme specificity.RSC chemical biology · 2026Review
- An amplification mechanism for weak ELF magnetic fields quantum-bio effects in cancer cells.Scientific reports · 2025Article
- The cytochrome bPhotosynthesis research · 2024Review
- Article
- Unexpected Heme Redox Potential Values Implicate an Uphill Step in CytochromeThe journal of physical chemistry. B · 2022Article
- The assembly, regulation and function of the mitochondrial respiratory chain.Nature reviews. Molecular cell biology · 2022Review
- Catalytic Reactions and Energy Conservation in the CytochromeChemical reviews · 2021Review
- The High-Spin HemeFrontiers in chemistry · 2021Article
- Analysis of a Functional Dimer Model of Ubiquinol Cytochrome c Oxidoreductase.Biophysical journal · 2017Article
- Metastable radical state, nonreactive with oxygen, is inherent to catalysis by respiratory and photosynthetic cytochromes bc1/b6f.Proceedings of the National Academy of Sciences of the United States of America · 2017Article
- Identifying involvement of Lys251/Asp252 pair in electron transfer and associated proton transfer at the quinone reduction site of Rhodobacter capsulatus cytochrome bc1.Biochimica et biophysica acta · 2016Article
- The quantum mitochondrion and optimal health.Biochemical Society transactions · 2016Article
- Energy conversion, redox catalysis and generation of reactive oxygen species by respiratory complex I.Biochimica et biophysica acta · 2016Review
- Distinct properties of semiquinone species detected at the ubiquinol oxidation Qo site of cytochrome bc1 and their mechanistic implications.Journal of the Royal Society, Interface · 2016Review
- Tuning of Hemes b Equilibrium Redox Potential Is Not Required for Cross-Membrane Electron Transfer.The Journal of biological chemistry · 2016Article
- Impact of Antioxidants on Cardiolipin Oxidation in Liposomes: Why Mitochondrial Cardiolipin Serves as an Apoptotic Signal?Oxidative medicine and cellular longevity · 2016Article
- Mitochondrial Disease-related Mutation G167P in Cytochrome b of Rhodobacter capsulatus Cytochrome bc1 (S151P in Human) Affects the Equilibrium Distribution of [2Fe-2S] Cluster and Generation of Superoxide.The Journal of biological chemistry · 2015Article
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Authors and funding
4 authors at 1 institution in 1 country.
Funding
Abstract
Efficient energy conversion often requires stabilization of one-electron intermediates within catalytic sites of redox enzymes. While quinol oxidoreductases are known to stabilize semiquinones, one of the famous exceptions includes the quinol oxidation site of cytochrome bc1 (Qo), for which detection of any intermediate states is extremely difficult. Here we discover a semiquinone at the Qo site (SQo) that is coupled to the reduced Rieske cluster (FeS) via spin-spin exchange interaction. This interaction creates a new electron paramagnetic resonance (EPR) transitions with the most prominent g = 1.94 signal shifting to 1.96 with an increase in the EPR frequency from X- to Q-band. The estimated value of isotropic spin-spin exchange interaction (|J0| = 3500 MHz) indicates that at a lower magnetic field (typical of X-band) the SQo-FeS coupled centers can be described as a triplet state. Concomitantly with the appearance of the SQo-FeS triplet state, we detected a g = 2.0045 radical signal that corresponded to the population of unusually fast-relaxing SQo for which spin-spin exchange does not exist or is too small to be resolved. The g = 1.94 and g = 2.0045 signals reached up to 20% of cytochrome bc1 monomers under aerobic conditions, challenging the paradigm of the high reactivity of SQo toward molecular oxygen. Recognition of stable SQo reflected in g = 1.94 and g = 2.0045 signals offers a new perspective on understanding the mechanism of Qo site catalysis. The frequency-dependent EPR transitions of the SQo-FeS coupled system establish a new spectroscopic approach for the detection of SQo in mitochondria and other bioenergetic systems.
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