Abstract:
:The Na(+)-pumping NADH:quinone oxidoreductase (Na(+)-NQR) is a fundamental enzyme of the oxidative phosphorylation metabolism and ionic homeostasis in several pathogenic and marine bacteria. To understand the mechanism that couples electron transfer with sodium translocation in Na(+)-NQR, the ion dependence of the redox potential of the individual cofactors was studied using a spectroelectrochemical approach. The redox potential of one of the FMN cofactors increased 90 mV in the presence of Na(+) or Li(+), compared to the redox potentials measured in the presence of other cations that are not transported by the enzyme, such as K(+), Rb(+), and NH(4)(+). This shift in redox potential of one FMN confirms the crucial role of the FMN anionic radicals in the Na(+) pumping mechanism and demonstrates that the control of the electron transfer rate has both kinetic (via conformational changes) and thermodynamic components.
journal_name
Biochemistryjournal_title
Biochemistryauthors
Neehaul Y,Juárez O,Barquera B,Hellwig Pdoi
10.1021/bi300343usubject
Has Abstractpub_date
2012-05-15 00:00:00pages
4072-7issue
19eissn
0006-2960issn
1520-4995journal_volume
51pub_type
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