title: Oxygenated iron bleomycin. A short-lived intermediate in the reaction of ferrous bleomycin with O2.
abstract: The reaction of Fe(II) . bleomycin with O2 to yield Fe(III) . bleomycin has been resolved into two kinetic events by stopped-flow spectrophotometry. The first event is first order with respect to both bleomycin and O2 and may be regarded as a second order reaction (k = 6.1 x 10(3) M-1s-1 at 2 degrees C). The first product has no EPR spectrum. The optical spectrum resembles those of Fe(II) . bleomycin complexes with CO, NO, and ethyl isocyanide. We propose that the first product is an Fe(II) . bleomycin . O2 complex. The second kinetic event is first order with respect to the first accumulated product (k = 0.11 s-1 at 2 degrees C) and independent of oxygen concentration. The product of this reaction is indistinguishable from Fe(III) . bleomycin by optical and EPR spectroscopy.
mesh_terms: D001761:Bleomycin; D002248:Carbon Monoxide; D055598:Chemical Phenomena; D002621:Chemistry; D003486:Cyanides; D004578:Electron Spin Resonance Spectroscopy; D007501:Iron; D007700:Kinetics; D008024:Ligands; D009569:Nitric Oxide; D010100:Oxygen; D013053:Spectrophotometry
chemical_list: D003486:Cyanides; D008024:Ligands; D001761:Bleomycin; D009569:Nitric Oxide; D002248:Carbon Monoxide; D007501:Iron; D010100:Oxygen