NMR studies of 4-methylimidazole binding to cytochrome c: effects of methyl substituent on the binding affinity, the orientation of the ligand plane,and the electronic structure of the heme
Y. Yao et al., NMR studies of 4-methylimidazole binding to cytochrome c: effects of methyl substituent on the binding affinity, the orientation of the ligand plane,and the electronic structure of the heme, J CHEM S DA, (22), 2000, pp. 4069-4074
Citations number
34
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
The binding of 4-methylimidazole (mim) to cytochrome c (cyt c) has been stu
died by H-1 NMR spectroscopy. The kinetic and thermodynamic parameters for
the reaction were calculated. The assignment of a number of signals has led
to the determination of the magnetic susceptibility tensor of mim-cyt c. I
t turned out that the orientation of the imidazole ring of mim was differen
t from that of Him in Him-cyt c. This difference was due to the steric inte
raction between the 4-methyl and the surrounding peptides in the heme cavit
y. The pseudocontact and contact shifts of the four heme methyl groups in m
im-cyt c were calculated. The hyperfine shift pattern and heme electron str
ucture of mim-cyt c were compared with those of native cyt c and Him-cyt c.