Viola F, Aime S, Coletta M, Desideri A, Fasano M, Paoletti S, Tarricone C, Ascenzi P. Azide, cyanide, fluoride, imidazole and pyridine binding to ferric and ferrous native horse heart cytochrome c and to its carboxymethylated derivative: a comparative study.
J Inorg Biochem 1996;
62:213-22. [PMID:
8627283 DOI:
10.1016/0162-0134(95)00155-7]
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Abstract
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.
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