The solution structures of tuna and horse cytochromes c

The nuclear magnetic resonance spectra of tuna ferricytochrome c and tuna ferrocytochrome c are described. Resonance assignments are made using NMR double-resonance techniques. A comparison of the NMR data for tuna cytochrome c with the previously reported data for horse cytochrome c shows that the proteins have virtually identical main-chain folds. Three regions of local conformational differences have been distinguished.