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Thiol/disulfide formation associated with the redox activity of the [Fe3S4] cluster of Desulfovibrio gigas ferredoxin II. 1H NMR and Mossbauer spectroscopic study

1994-01-01Artigo científico Acesso aberto
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dc.contributor.authorMacedo, A. L.
dc.contributor.authorMoura, I.
dc.contributor.authorSurerus, K. K.
dc.contributor.authorPapaefthymiou, V.
dc.contributor.authorLiu, M. Y.
dc.contributor.authorLeGall, J.
dc.contributor.authorMunck, E.
dc.contributor.authorMoura, José J. G.
dc.contributor.institutionDQ - Departamento de Química
dc.contributor.institutionInstituto de Tecnologia Química e Biológica António Xavier (ITQB)
dc.contributor.pblASBMB - American Society for Biochemistry and Molecular Biology
dc.date.accessioned2019-09-10T22:49:37Z
dc.date.available2019-09-10T22:49:37Z
dc.date.issued1994-01-01
dc.descriptionNIGMS NIH HHS (GM-41482)
dc.description.abstractDesulfovibrio gigas ferredoxin II (FdII) is a small protein (α4 subunit structure as isolated; M(r) ≃ 6400 per subunit; 6 cysteine residues) containing one Fe3S4 cluster per α-subunit. The x-ray structure of FdII has revealed a disulfide bridge formed by Cys-18 and Cys-42 approximately 13 Å away from the center of the cluster; moreover, the x-ray structure indicates that Cys-11 forms a disulfide bridge with a methanethiol. In the oxidized state, FdII(ox), the 1H NMR spectra, exhibit four low-field contact-shifted resonances at 29, 24, 18, and 15.5 ppm whereas the reduced state, FdII(R) (S = 2), yields two features at +18.5 and -11 ppm. In the course of studying the redox behavior of FdII, we have discovered a stable intermediate, FdII(int), that yields 1H resonances at 24, 21.5, 21, and 14 ppm. This intermediate appears in the potential range where the cluster (E'0 ≃ -130 mV) is reduced from the [Fe3S4]1+ to the [Fe3S4]0 state. FdII(int) is observed during reductive titrations with dithionite or hydrogen/hydrogenase or after partial oxidation of FdII(R) by 2,6- dichlorophenolindophenol or air. Our studies show that a total of three electrons per α-subunit are transferred to FdII. Our experiments demonstrate the absence of a methanethiol-Cys-11 linkage in our preparations, and we propose that two of the three electrons are used for the reduction of the disulfide bridge. Mossbauer (and EPR) studies show that the Fe3S4 cluster of FdII(int) is at the same oxidation level as FdII(ox), but indicate some changes in the exchange couplings among the three ferric sites. Our data suggest that the differences in the NMR and Mossbauer spectra of FdII(ox) and FdII(int) result from conformational changes attending the breaking or formation of the disulfide bridge. The present study suggests that experiments be undertaken to explore an in vivo redox function for the disulfide bridge.en
dc.description.versionpublishersversion
dc.description.versionpublished
dc.format.extent7
dc.format.extent833237
dc.identifier.issn0021-9258
dc.identifier.otherPURE: 14636065
dc.identifier.otherPURE UUID: 6e53dd57-68d7-4d0f-84fc-fa16414fbf55
dc.identifier.otherScopus: 0028365050
dc.identifier.otherPubMed: 8132528
dc.identifier.otherWOS: A1994NB40900036
dc.identifier.otherORCID: /0000-0002-4726-2388/work/68772138
dc.identifier.urihttp://www.scopus.com/inward/record.url?scp=0028365050&partnerID=8YFLogxK
dc.identifier.urlhttps://www.scopus.com/pages/publications/0028365050
dc.language.isoeng
dc.peerreviewedyes
dc.subjectBiochemistry
dc.subjectMolecular Biology
dc.subjectCell Biology
dc.titleThiol/disulfide formation associated with the redox activity of the [Fe3S4] cluster of Desulfovibrio gigas ferredoxin II. 1H NMR and Mossbauer spectroscopic studyen
dc.typejournal article
degois.publication.firstPage8052
degois.publication.issue11
degois.publication.lastPage8058
degois.publication.titleJournal of Biological Chemistry
degois.publication.volume269
dspace.entity.typePublication
rcaap.rightsopenAccess

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