1.14.99.58 Carr-Purcell-Meiboom-Gill NMR study on ferric enzyme state inhibited by cyanide and azide, and its ferrous state inhibited by carbon monoxide. The nature of the coordinated distal ligand affects the conformational freedom of the polypeptide in regions of the enzyme far removed from the heme iron and distal ligand. In addition to proton delivery to the nascent FeIII-OO- intermediate during catalysis, the hydrogen-bonding network serves to propagate the electronic state in each of the distinct steps of the catalytic cycle to key but remote sections of the polypeptide and to modulate the conformational freedom of the enzyme 680357 1.14.99.58 NMR-spectroscopy studies of paramagnetic cyanide-inhibited and azide-inhibited enzyme forms. The protein in the azide-inhibited complex is significantly less prone to H/D exchange than the cyanide-inhibited form. Unpaired spin delocalization from the heme iron into the G15-N atom via formation of a hydrogen bond between the coordinated azide nitrogen and the G125 N-H 678184