Reduction of oxidized cytochrome c by ascorbate ion.
The kinetics and mechanism of the reduction of oxidized cytochrome c by ascorbate has been investigated in potassium nitrate, potassium 4-morpholineethanesulfonate (KMes), potassium sulfate and potassium ascorbate media. The results are consistent with simple second order electron transfer from ascorbate dianion to cytochrome c and do not support electron transfer from an ascorbate dianion bound to the protein of the cytochrome as recently proposed by Myer and Kumar. A rate constant of 8 X 10(5) M-1 X s-1 (25 degrees C, ionic strength, 0.1) was found for the electron-transfer step. This rate constant is essentially independent of the specific ions used in controlling ionic strength.
D000476:Alkanesulfonates; D017738:Alkanesulfonic Acids; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D003574:Cytochrome c Group / Q000378:metabolism*; D004579:Electron Transport; D006736:Horses; D007700:Kinetics; D009025:Morpholines; D009206:Myocardium / Q000201:enzymology; D009566:Nitrates; D010084:Oxidation-Reduction; D017680:Potassium Compounds; D012996:Solutions; D013431:Sulfates
D000476:Alkanesulfonates; D017738:Alkanesulfonic Acids; D003574:Cytochrome c Group; D009025:Morpholines; D009566:Nitrates; D017680:Potassium Compounds; D012996:Solutions; D013431:Sulfates; C031512:potassium sulfate; C004550:2-(N-morpholino)ethanesulfonic acid; D001205:Ascorbic Acid; C023844:potassium nitrate