Proton NMR probe for hydrogen bonding of distal residues to bound ligands in heme proteins: isotope effect on heme electronic structure of myoglobin

Abstract

The authors demonstrate herein an isotope effect on the electronic structure of the heme in the low-spin, ferric cyanide complex of sperm whale myoglobin, metMbCN, which can be uniquely attributed to an H-bond between the distal (E7) histidyl imidazole and the bound ligand. The perturbation of the heme electronic structure arises directly from the isotope effect of the H bond between the distal His number7 and the bound ligand.