title: The reaction of superoxide, formate radical, and hydrated electron with transferrin and its model compound, Fe(III)-ethylenediamine-N,N'-bis[2-(2-hydroxyphenyl)acetic acid] as studied by pulse radiolysis.
abstract: Transferrin and the transferrin model compound Fe(III)-EHPG (Fe(III)-ethylenediamine-N,N'-bis[2-(2-hydroxyphenyl)acetic acid] were found not to react with superoxide, as pulse radiolysis and kinetic spectroscopy revealed no transient species and no bleaching of the 465-nm absorption. However, transferrin was found to react with the formate radical, CO-.2, and the hydrated electron, e-aq, with second-order rate constants of 3.8 X 10(8) and 1.1 X 10(10) M-1 S-1, respectively. These reactions produced a transient species (lambda max = 420 nm) which subsequently decayed by a second-order process. However, no reduction of the Fe(III) in transferrin was detected. Fe(III)-EHPG was also found to react with CO-.2 and e-aq, k = 7.3 X 10(6) and 1.1 X 10(9) M-1 S-1, respectively. The reactions of CO-.2 and e-aq with Fe(III)-EHPG resulted in no transient species but rather in reduction of the iron. These results are consistent with the inability of transferrin and Fe(III)-EHPG to catalyze the Haber-Weiss reaction.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D004583:Electrons; D005029:Ethylenediamines / Q000378:metabolism*; D005561:Formates / Q000378:metabolism*; D005609:Free Radicals; D006801:Humans; D007700:Kinetics; D011675:Pulse Radiolysis; D013481:Superoxides / Q000378:metabolism*; D014168:Transferrin / Q000378:metabolism*
chemical_list: D005029:Ethylenediamines; D005561:Formates; D005609:Free Radicals; D014168:Transferrin; C030544:formic acid; D013481:Superoxides; C011813:ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid)