Feb 18, 2014

Redox tuning of the catalytic activity of soluble fumarate reductases from Shewanella

Biochimica Et Biophysica Acta
Catarina M PaqueteRicardo O Louro

Abstract

Many enzymes involved in bioenergetic processes contain chains of redox centers that link the protein surface, where interaction with electron donors or acceptors occurs, to a secluded catalytic site. In numerous cases these redox centers can transfer only single electrons even when they are associated to catalytic sites that perform two-electron chemistry. These chains provide no obvious contribution to enhance chemiosmotic energy conservation, and often have more redox centers than those necessary to hold sufficient electrons to sustain one catalytic turnover of the enzyme. To investigate the role of such a redox chain we analyzed the transient kinetics of fumarate reduction by two flavocytochromes c3 of Shewanella species while these enzymes were being reduced by sodium dithionite. These soluble monomeric proteins contain a chain of four hemes that interact with a flavin adenine dinucleotide (FAD) catalytic center that performs the obligatory two electron-two proton reduction of fumarate to succinate. Our results enabled us to parse the kinetic contribution of each heme towards electron uptake and conduction to the catalytic center, and to determine that the rate of fumarate reduction is modulated by the redox stage of the e...Continue Reading

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  • Citations2

Citations

Mentioned in this Paper

Metabolic Process, Cellular
Fluctuation
Sodium Dithionite
Enzymes, antithrombotic
Succinate Dehydrogenase
Protein NMR Spectroscopy
Uptake
Electron Transport
Succinates
Cell Respiration

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