title: The reduction of porphyrin cytochrome c by hydrated electrons and the subsequent electron transfer reaction from reduced porphyrin cytochrome c to ferricytochrome c.
abstract: 1. Hydrated electrons, produced by pulse radiolysis react with porphyrin cytochrome c with a bimolecular rate constant of 3-10(10) M-1 S-1 at 21 degrees C and pH 7.4. 2. After the reduction step an absorbance change with a half-life of 5 microns is observed with the spectral range of 430-470 nm. A relatively stable intermediate then decays with a half-life of 15 s. 3. The spectrum of the intermediate observed 50 microns after the generation of hydrated electrons shows a broad absorption band between 600 and 700 nm and a peak at 408 nm. The spectrum is attributed to the protonated form of an initially produced porphyrin anion radical. 4. Reduced porphyrin cytochrome c reacts with ferricytochrome c with a bimolecular constant of 2-10(5) M-1- S-1 in 2 mM phosphate pH 7.4, at 21 degrees C and of 2 - 10(6) M-1-S-1 under the same conditions but at 1 M ionic strength. It is proposed that electron transfer in an analogous exchange reaction between ferrocytochrome c and ferricytochrome c occurs via the exposed part of the haem.
mesh_terms: D000818:Animals; D003574:Cytochrome c Group / Q000378:metabolism*; D004553:Electric Conductivity; D004579:Electron Transport; D004583:Electrons; D006736:Horses; D009206:Myocardium; D009994:Osmolar Concentration; D010084:Oxidation-Reduction
chemical_list: D003574:Cytochrome c Group