Open AccessNUCLEAR MAGNETIC RESONANCES OF RECONSTITUTED MYOGLOBINS
Author(s) -
R. G. Shulman,
Kurt Wüthrich,
Toshimi Yamane,
Eraldo Antonini,
Maurizio Brunori
Publication year - 1969
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.63.3.623
Subject(s) - heme , unpaired electron , chemistry , proton , nuclear magnetic resonance , resonance (particle physics) , crystallography , hemeprotein , proton nmr , electron nuclear double resonance , stereochemistry , electron paramagnetic resonance , atomic physics , molecule , physics , organic chemistry , quantum mechanics , enzyme
In proton nuclear magnetic resonance spectra of paramagnetic heme proteins, the resonances of the heme groups are shifted away from those of the many hundred protons of the polypeptide chains by interactions with the unpaired electrons and are therefore well resolved at 220 Mc. This paper describes experiments from which these resolved resonances are assigned to specific protons of the heme group in cyanoferrimyoglobin. From a comparison with the proton nuclear magnetic resonance spectra of reconstituted cyanoferrimyoglobins and the corresponding cyanoporphyrin iron (III) complexes, the following groups of heme-protons have been assigned to specific resonances in the NMR spectrum of native cyanoferrimyoglobin: the four ring methyls, the four meso protons, the two -CH groups of the vinyls, and the four methylenes of the propionate side chains. Two resonances of intensity one proton have been assigned to the proximal histidyl residue. The only heme protons whose resonances were not observed are the [unk]CH2 groups of the vinyl groups which are probably buried in the bulk spectrum of the polypeptide chain. The present data indicate that the protein environment is more important in determining the distribution of unpaired electron density in the heme group than are the heme substituents.