Binding of 1-methylimidazole to cytochrome c: kinetic analysis and resonance assignments by two-dimensional NMR.
The binding of 1-methylimidazole to the heme iron by displacing Met-80 of cytochrome c has been studied by two-dimensional (2D) exchange spectroscopy. Two components of cytochrome c ligated by 1-methylimidazole (1-MeIm-cyt c) are first identified, which are related to the sterically hindered orientation of 1-methylimidazole by the heme pocket. Based on a matrix formalism, the kinetic parameters are calculated from the 2D peak amplitudes. With the known resonance assignments of cytochrome c, some hyperfine shifted resonances arising from heme peripheral protons and two axial ligands, and some side-chain resonances of the aliphatic and aromatic protons of 1-MeIm-cyt c have been straightforwardly assigned, which provide a clue to ligand-induced electronic and molecular structural changes of the protein.
Shao
W
W
State Key Laboratory of Coordination Chemistry, Nanjing University, People's Republic of China.
Liu
G
G
Tang
W
W
D003574:Cytochrome c Group / Q000737:chemistry*; D006418:Heme / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D011522:Protons
D003574:Cytochrome c Group; D007093:Imidazoles; D011522:Protons; D006418:Heme; C018100:1-methylimidazole