title: Formation of tryptophan radicals in irradiated aqueous solutions of hexachloroplatinate(IV): a flash photolysis study.
abstract: The oxidation of tryptophan photosensitized by PtCl6(2-) has been investigated in aqueous solutions at different pH using nanosecond laser flash photolysis. Cationic and neutral radicals of tryptophan were detected at pH 2.8 and 8.5, respectively. The generation of the radical was attributed to oxidation by Cl2- that was formed from the homolytic bond cleavage in the excited state of PtCl6(2-). The bimolecular rate constant derived from the kinetics analysis, 2.8 +/- 0.2 x 10(9) M-1 s-1, is in good agreement with the value obtained in earlier pulse radiolysis studies. Both the cationic and neutral radicals decayed by second-order kinetics, consistent with the dimerization process.
authors.affiliation: Department of Chemistry, Bowling Green State University, OH 43403, USA.
authors.forename: L
authors.initials: L
authors.lastname: Zang
authors.forename: M A
authors.initials: MA
authors.lastname: Rodgers
mesh_terms: D002945:Cisplatin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000528:radiation effects; D019281:Dimerization; D005609:Free Radicals / Q000737:chemistry / Q000528:radiation effects; D066298:In Vitro Techniques; D010782:Photolysis; D012996:Solutions; D014364:Tryptophan / Q000737:chemistry / Q000528:radiation effects*; D014867:Water
chemical_list: D005609:Free Radicals; D012996:Solutions; D014867:Water; D014364:Tryptophan; D002945:Cisplatin; C038762:disodium hexachloroplatinate