H-1-NMR STUDIES OF PYRIDINE BINDING TO METMYOGLOBIN

Two-dimensional H-1 nuclear magnetic resonance exchange spectroscopy h as been applied to the study of the pyridine-ligated complex of equine metmyoglobin (Py-metMb). With the known resonance assignment of metMb , some hyperfine shifted resonances of the Py-metMb complex have been assigned for the first time. Based on a matrix formalism, the kinetic and equilibrium data for pyridine binding to metMb have been evaluated from the 2D peak amplitudes. A qualitative comparison of the methyl s hift pattern in metMbCN(-), metMbN(3)(-) and imidazole metMb (metMbIm) with Py-metMb shows a reverse methyl shift between pyrrole I and IV, and the reason for this is discussed.