ArticleBiochimica et biophysica acta2013
Role of the -PEWY-glutamate in catalysis at the Q(o)-site of the Cyt bc(1) complex.
Article in Biochimica et biophysica acta, 2013. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 17 papers.
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Who cites it
17 citing papers in PubMed.
- Recent insights into the molecular mechanism of ubiquinol oxidation by cytochrome bcFEBS open bio · 2026Review
- Article
- Flexibility and Hydration of the QJournal of chemical information and modeling · 2025Article
- The cytochrome bPhotosynthesis research · 2024Review
- Cryo-EM structure of the four-subunitProceedings of the National Academy of Sciences of the United States of America · 2023Article
- Catalytic Reactions and Energy Conservation in the CytochromeChemical reviews · 2021Review
- In Silico Modeling of the Mitochondrial Pumping Complexes with Markov State Models.Methods in molecular biology (Clifton, N.J.) · 2021Article
- The High-Spin HemeFrontiers in chemistry · 2021Article
- Universal free-energy landscape produces efficient and reversible electron bifurcation.Proceedings of the National Academy of Sciences of the United States of America · 2020Article
- Modelling mitochondrial ROS production by the respiratory chain.Cellular and molecular life sciences : CMLS · 2020Review
- Dissecting the pattern of proton release from partial process involved in ubihydroquinone oxidation in the Q-cycle.Biochimica et biophysica acta. Bioenergetics · 2018Article
- The cytochrome b Zn binding amino acid residue histidine 291 is essential for ubihydroquinone oxidation at the QBiochimica et biophysica acta · 2016Article
- Communication: Microsecond dynamics of the protein and water affect electron transfer in a bacterial bc(1) complex.The Journal of chemical physics · 2015Article
- Identification of ubiquinol binding motifs at the Qo-site of the cytochrome bc1 complex.The journal of physical chemistry. B · 2015Article
- Mechanism of enhanced superoxide production in the cytochrome b(6)f complex of oxygenic photosynthesis.Biochemistry · 2013Article
- Transmembrane signaling and assembly of the cytochrome b6f-lipidic charge transfer complex.Biochimica et biophysica actaReview
- The mechanism of ubihydroquinone oxidation at the Qo-site of the cytochrome bc1 complex.Biochimica et biophysica actaReview
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3 authors.
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Abstract
We re-examine the pH dependence of partial processes of ubihydroquinone (QH(2)) turnover in Glu-295 mutants in Rhodobacter sphaeroides to clarify the mechanistic role. In more crippled mutants, the bell-shaped pH profile of wildtype was replaced by dependence on a single pK at ~8.5 favoring electron transfer. Loss of the pK at 6.5 reflects a change in the rate-limiting step from the first to the second electron transfer. Over the range of pH 6-8, no major pH dependence of formation of the initial reaction complex was seen, and the rates of bypass reactions were similar to the wildtype. Occupancy of the Q(o)-site by semiquinone (SQ) was similar in the wildtype and the Glu→Trp mutant. Since heme b(L) is initially oxidized in the latter, the bifurcated reaction can still occur, allowing estimation of an empirical rate constant <10(3)s(-1) for reduction of heme b(L) by SQ from the domain distal from heme b(L), a value 1000-fold smaller than that expected from distance. If the pK ~8.5 in mutant strains is due to deprotonation of the neutral semiquinone, with Q(•-) as electron donor to heme b(L), then in wildtype this low value would preclude mechanisms for normal flux in which semiquinone is constrained to this domain. A kinetic model in which Glu-295 catalyzes H(+) transfer from QH•, and delivery of the H(+) to exit channel(s) by rotational displacement, and facilitates rapid electron transfer from SQ to heme b(L) by allowing Q(•-) to move closer to the heme, accounts well for the observations.
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