Solution structure of the imidazole complex of cytochrome c

The solution structure of the imidazole adduct of oxidized horse heart cyto chrome c(Im-cyt c) has been determined through 2D NMR spectroscopy. The 35 conformers of the family show the RMSD values to the average structure of 0 .063 +/-0.007 nm for the backbone and 0.107 +/-0.007 nm for all heavy atoms , respectively. The secondary structure elements and the overall folding of the present structure are substantially similar to those of the solution s tructure of native protein. However, the replacement of the axial ligand Me t 80 with the exogenous imidazole ligand induces significant conformation c hanges in both backbone and side chains of the residues locating in the dis tal axial ligand regions. The electron delocalization on the heme moiety an d the magnetic susceptibility tenser are consistent with these structural f eatures.