title: GPx-Like activity of selenides and selenoxides: experimental evidence for the involvement of hydroxy perhydroxy selenane as the active species.
abstract: The reaction mechanism of the GPx-like oxidation of PhSH with H(2)O(2) catalyzed by selenoxides proceeds via formation of the hydroxy perhydroxy selenane, which is a stronger oxidizing agent than selenoxide. A hydroxy perhydroxy selenane intermediate was observed by electrospray ionization mass spectrometry and (77)Se NMR spectroscopy in reactions of selenoxide 8 with H(2)O(2).The initial velocity of oxidation of PhSH by H(2)O(2) with selenoxide 8 is 4 orders of magnitude higher than that of 8 without peroxide. Selenoxide 8 is not reduced to selenide 6 by PhSH in the presence of H(2)O(2). While electronic substituent effects have minimal impact on the catalytic performance of selenoxides, chelating groups increase the rate of catalysis.
authors.affiliation: Department of Chemistry, Federal University of Santa Catarina, Florianópolis-SC, Brazil.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Nascimento
authors.forename: Eduardo E
authors.initials: EE
authors.lastname: Alberto
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Tondo
authors.forename: Daniel
authors.initials: D
authors.lastname: Dambrowski
authors.forename: Michael R
authors.initials: MR
authors.lastname: Detty
authors.forename: Faruk
authors.initials: F
authors.lastname: Nome
authors.forename: Antonio L
authors.initials: AL
authors.lastname: Braga
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry*; D002384:Catalysis; D005979:Glutathione Peroxidase; D006861:Hydrogen Peroxide / Q000737:chemistry; D016566:Organoselenium Compounds / Q000737:chemistry*
chemical_list: D016566:Organoselenium Compounds; D006861:Hydrogen Peroxide; D005979:Glutathione Peroxidase