Iverson 2013 Biochim Biophys Acta
| Iverson TM (2013) Catalytic mechanisms of complex II enzymes: a structural perspective. Biochim Biophys Acta 1827:648-57. https://doi.org/10.1016/j.bbabio.2012.09.008 |
Iverson TM (2013) Biochim Biophys Acta
Abstract: Over a decade has passed since the elucidation of the first X-ray crystal structure of any complex II homolog. In the intervening time, the structures of five additional integral-membrane complex II enzymes and three homologs of the soluble domain have been determined. These structures have provided a framework for the analysis of enzymological studies of complex II superfamily enzymes, and have contributed to detailed proposals for reaction mechanisms at each of the two enzyme active sites, which catalyze dicarboxylate and quinone oxidoreduction, respectively. This review focuses on how structural data have augmented our understanding of catalysis by the superfamily. This article is part of a Special Issue entitled: Respiratory complex II: Role in cellular physiology and disease.
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- .. electrons enter the electron transport chain through either complex I or complex II. Complex II bridges the processes of oxidative phosphorylation with the Krebs cycle, thus linking these two energy harvesting processes in higher organisms.
- Complex II enzymes couple two distinct chemical reactions: the reversible oxidoreduction of succinate and fumarate, catalyzed in a soluble domain, and the reversible oxidoreduction of quinol and quinone, which is catalyzed in a membrane-spanning domain.
- Succinate:quinone oxidoreductases (SQRs, succinate dehydrogenases, SdhABCD) are kinetically advantaged to oxidize succinate and reduce quinone, a reaction important for aerobic respiration. Conversely, quinol:fumarate reductases (QFRs, fumarate reductases, FrdABCD) are kinetically advantaged to catalyze the reverse reaction, i.e. to reduce fumarate and oxidize quinol . No matter the preferred direction of the reaction, complex II superfamily enzymes share a global architecture with a large soluble domain and a smaller integral-membrane domain.
- ..two distinct active sites (Fig. 1), one within the soluble domain that catalyzes the 2H+/2e− interconversion of succinate and fumarate (dicarboxyate interconversion site; Fig. 3), and one within the membrane spanning regions where quinone and quinol (collectively termed “Q” here if an oxidation state is not implied) are interconverted (Q-site; Fig. 2D–F).
Labels:
Preparation: Enzyme
Enzyme: Complex II;succinate dehydrogenase
