Characterization of cytochrome c from Nitrobacter Agilis

Cytochrome c from Nitrobacter agilis was isolated and purified approx. 60-fold. Absorption spectra of both the oxidized and the reduced Nitrobacter cytochrome c and the oxidized minus reduced difference spectrum of this cytochrome were essentially identical to the corresponding spectra of horse-heart cytochrome c. The redox potential of this cytochrome was determined by spectrophotometric titration with ferrocyanide/ferricyanide and found to be +0.282 V over the pH range 6.0 to 8.7, while a potential of +0.265 V was determined in the same manner for horse-heart cytochrome c. The titration also indicated that the Nitrobacter ferrocytochrome is oxidized by a single electron transfer.