title: Copper-substituted forms of the wild type and C42A variant of rubredoxin.
abstract: In order to gain insights into the interplay between Cu(I) and Cu(II) in sulfur-rich protein environments, the first preparation and characterization of copper-substituted forms of the wild-type rubredoxin (Rd) from Desulfovibrio vulgaris Hildenborough are reported, as well as those of its variant C42A-Rd. The initial products appear to be tetrahedral Cu(I)(S-Cys)n species for the wild type (n=4) and the variant C42A (n=3, with an additional unidentified ligand). These species are unstable to aerial oxidation to products, whose properties are consistent with square planar Cu(II)(S-Cys)n species. These Cu(II) intermediates are susceptible to auto-reduction by ligand S-Cys to produce stable Cu(I) final products. The original Cu(I) center in the wild-type system can be regenerated by reduction, suggesting that the active site can accommodate Cu(I)(S-Cys)2 and Cys-S-S-Cys fragments in the final product. The absence of one S-Cys ligand prevents similar regeneration in the C42A-Rd system. These results emphasize the redox instability of Cu(II)-(S-Cys)n centers.
authors.affiliation: Department of Photochemistry and Molecular Science, Uppsala University, P.O. Box 523, S-751 20 Uppsala, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Thapper
authors.forename: Alberto C
authors.initials: AC
authors.lastname: Rizzi
authors.forename: Carlos D
authors.initials: CD
authors.lastname: Brondino
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Wedd
authors.forename: Ricardo J
authors.initials: RJ
authors.lastname: Pais
authors.forename: Biplab K
authors.initials: BK
authors.lastname: Maiti
authors.forename: Isabel
authors.initials: I
authors.lastname: Moura
authors.forename: Sofia R
authors.initials: SR
authors.lastname: Pauleta
authors.forename: José J G
authors.initials: JJ
authors.lastname: Moura
mesh_terms: D003300:Copper / Q000737:chemistry*; D014644:Genetic Variation; D015394:Molecular Structure; D012416:Rubredoxins / Q000737:chemistry* / Q000235:genetics
chemical_list: D012416:Rubredoxins; D003300:Copper
keywords: Copper-substituted iron–sulfur center; EPR; Mutant coordination site; Rubredoxin; UV–visible