Azide, cyanide, fluoride, imidazole and pyridine binding to ferric and ferrous native horse heart cytochrome c and to its carboxymethylated derivative: a comparative study.
Azide, cyanide, fluoride, imidazole, and pyridine binding to ferric and ferrous native horse heart cytochrome c and to its carboxymethylated derivative has been investigated, from the thermodynamic viewpoint, at pH 7.5 and 25.0 degrees C. Ligand affinity for ferric and ferrous carboxymethylated cytochrome c is higher by about 30- and 400-fold, respectively, than that observed for the native protein. The results here reported: (i) allow the estimation, for the first time, of the ligand-independent free energy associated with the heme-iron sixth coordination bond in ferric and ferrous native cytochrome c, which turns out to be +8.4 kJ mol-1 and +14.6 kJ mol-1, at 25.0 degrees C, respectively, and (ii) suggest an interplay between redox, structural, ligand binding, and recognition properties of cytochrome c.
Viola
F
F
FV. Institute of Applied Pharmaceutical Chemistry, University of Turin, Italy.
Aime
S
S
Coletta
M
M
Desideri
A
A
Fasano
M
M
Paoletti
S
S
Tarricone
C
C
Ascenzi
P
P
D000818:Animals; D001386:Azides / Q000737:chemistry; D003486:Cyanides / Q000737:chemistry; D003574:Cytochrome c Group / Q000737:chemistry*; D004579:Electron Transport; D005290:Ferric Compounds / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry; D006736:Horses; D007093:Imidazoles / Q000737:chemistry; D008745:Methylation; D009206:Myocardium / Q000201:enzymology; D010084:Oxidation-Reduction; D011485:Protein Binding; D011725:Pyridines / Q000737:chemistry
D001386:Azides; D003486:Cyanides; D003574:Cytochrome c Group; D005290:Ferric Compounds; D005296:Ferrous Compounds; D007093:Imidazoles; D011725:Pyridines; C029899:imidazole; C023666:pyridine; D005459:Fluorides