Nuclear-magnetic-resonance investigations of the biliverdin-apomyoglobin complex

The recently described biliverdin-apomyoglobin complex has been investigated by two-dimensional NMR methods and molecular modeling with respect to the geometry of the chromophore and its position within the myoglobin pocket. Nuclear Overhauser effect correlations between the ligand and apoprotein amino acid residues prove that the bile pigment assumes a cyclic helical conformation and a position similar to heme in native myoglobin.