A MULTIPHASE CD-113 NMR INVESTIGATION OF METALLOPORPHYRIN REORIENTATION IN CADMIUM-SUBSTITUTED MYOGLOBIN

Cd-113 NMR spectroscopy in both the solution and solid state has been used to investigate the role of the metal ion and the proximal histidi ne on metalloporphyrin reorientation in myoglobin. Heme disorder has b een known to exist for many years but understanding its mechanism has proved difficult due to the short-lived nature of the minor porphyrin isomer in native myoglobin. Cadmium-substituted myoglobin can be gener ated in one form which contains different insertion isomers or in anot her form which contains predominantly only one of these species. This allows for direct investigation of heme disorder in metal-substituted myoglobin.