Topic
Q cycle
About: Q cycle is a research topic. Over the lifetime, 185 publications have been published within this topic receiving 17499 citations.
Papers published on a yearly basis
Papers
TL;DR: The newly introduced concepts of the protonmotive ubiquinone cycle, or Q cycle, and of the cyclic loop 2–3 system, which represent developments of the redox loop concept, are shown to provide a promising basis for the evolution of a satisfactory theory.
1,294 citations
TL;DR: In this article, crystal structures of the 11-subunit bc1 complex from bovine heart reveal full views of this bifunctional enzyme, and the "Rieske" iron-sulfur protein subunit shows significant conformational changes in different crystal forms.
Abstract: Mitochondrial cytochrome bc1 complex performs two functions: It is a respiratory multienzyme complex and it recognizes a mitochondrial targeting presequence. Refined crystal structures of the 11-subunit bc1 complex from bovine heart reveal full views of this bifunctional enzyme. The "Rieske" iron-sulfur protein subunit shows significant conformational changes in different crystal forms, suggesting a new electron transport mechanism of the enzyme. The mitochondrial targeting presequence of the "Rieske" protein (subunit 9) is lodged between the two "core" subunits at the matrix side of the complex. These "core" subunits are related to the matrix processing peptidase, and the structure unveils how mitochondrial targeting presequences are recognized.
1,281 citations
TL;DR: X-ray crystal structures of the cytochrome bc1 complex from chicken, cow and rabbit in both the presence and absence of inhibitors of quinone oxidation, reveal two different locations for the extrinsic domain of one component of the enzyme, an iron–sulphur protein.
Abstract: The cytochrome bc1 is one of the three major respiratory enzyme complexes residing in the inner mitochondrial membrane. Cytochrome bc1 transfers electrons from ubiquinol to cytochrome c and uses the energy thus released to form an electrochemical gradient across the inner membrane. Our X-ray crystal structures of the complex from chicken, cow and rabbit in both the presence and absence of inhibitors of quinone oxidation, reveal two different locations for the extrinsic domain of one component of the enzyme, an iron-sulphur protein. One location is close enough to the supposed quinol oxidation site to allow reduction of the Fe-S protein by ubiquinol. The other site is close enough to cytochrome c1 to allow oxidation of the Fe-S protein by the cytochrome. As neither location will allow both reactions to proceed at a suitable rate, the reaction mechanism must involve movement of the extrinsic domain of the Fe-S component in order to shuttle electrons from ubiquinol to cytochrome c1. Such a mechanism has not previously been observed in redox protein complexes.
1,064 citations
TL;DR: The results of kinetic studies and electron turnover experiments suggest that Cd may bind between semiubiquinone and cy tochrome b566 of the Q0 site of cytochrome b of complex III, resulting in accumulation of semiUBiquinones at theQ0 site, providing a possible mechanism for Cd-induced generation of ROS in mitochondria.
681 citations
TL;DR: The object of this letter is to define the general principles of the protonmotive Q cycle more explicitly than before, thus facilitating either its experimental rejection or its further development and general application.
616 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 5 |
| 2020 | 1 |
| 2019 | 3 |
| 2018 | 2 |
| 2017 | 2 |
| 2016 | 5 |