title: The diffusion-controlled reaction of semioxidized tryptophan with the superoxide radical anion.
abstract: From pulse radiolysis measurements in oxygenated aqueous solution, the semioxidized tryptophan radical (Trp.- formed by the one-electron oxidation of Trp by Br2- radical--has been shown to oxidize the superoxide radical anion with a rate constant of k = 2 x 10(9) M-1 s-1. Proof of this reaction is found in addition of superoxide dismutase (SOD) to the system, which totally eliminates the contribution of the Trp. + O2- mechanism to Trp. decay. Little, if any, reaction of molecular oxygen with Trp. may be observed on the time scale of the pulse radiolysis experiment.
authors.affiliation: Laboratoire de Physico-Chimie de l'Adaptation Biologique, INSERM U 312, Muséum National d'Histoire Naturelle, Paris, France.
authors.forename: R
authors.initials: R
authors.lastname: Santus
authors.forename: L K
authors.initials: LK
authors.lastname: Patterson
authors.forename: M
authors.initials: M
authors.lastname: Bazin
mesh_terms: D000838:Anions; D001966:Bromine / Q000737:chemistry; D004058:Diffusion; D007700:Kinetics; D010084:Oxidation-Reduction; D011675:Pulse Radiolysis; D013482:Superoxide Dismutase / Q000494:pharmacology; D013481:Superoxides / Q000737:chemistry*; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D000838:Anions; D013481:Superoxides; D014364:Tryptophan; D013482:Superoxide Dismutase; D001966:Bromine