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Desulfovibrio gigas ferredoxin II: redox structural modulation of the [3Fe-4S] cluster
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Resumo(s)
Abstract Desulfovibrio gigas ferredoxin II (DgFdII) is a small protein with a polypeptide chain composed of 58 amino acids, containing one Fe3S4 cluster per monomer. Upon studying the redox cycle of this protein, we detected a stable intermediate (FdIIint) with four 1H resonances at 24.1, 20.5, 20.8 and 13.7 ppm. The differences between FdIIox and FdIIint were attributed to conformational changes resulting from the breaking/formation of an internal disulfide bridge. The same 1H NMR
methodology used to fully assign the three cysteinyl ligands of the [3Fe–4S] core in the oxidized state (DgFdIIox) was used here for the assignment of the same three ligands in the intermediate state (DgFdIIint). The
spin-coupling model used for the oxidized form of DgFdII where magnetic exchange coupling constants of around 300 cm 1 and hyperfine coupling constants equal to 1 MHz for all the three iron centres were found,
does not explain the isotropic shift temperature dependence for the three cysteinyl cluster ligands in DgFdIIint. This study, together with the spin delocalization mechanism proposed here for DgFdIIint, allows the detection of structural modifications at the [3Fe-4S] cluster in
DgFdIIox and DgFdIIint.
Descrição
Palavras-chave
Fe3S4 cluster Ferredoxin Disulfide bridge Paramagnetic protein Desulfovibrio gigas
Contexto Educativo
Citação
Rodrigues, P.M.; Macedo, A.L.; Goodfellow, B.J.; Moura, I.; Moura, J.J.G. Desulfovibrio gigas ferredoxin II: Redox structural modulation of the [3Fe-4S] cluster, Journal of Biological Inorganic Chemistry, 11, 3, 307-315, 2006.
Editora
Springer Verlag