High resolution nuclear magnetic resonance spectra of hemoglobin: I. The cyanide complexes of α and β chains

Abstract

The high resolution nuclear magnetic resonance spectra of the isolated chains of human hemoglobin have been studied. Interest is mainly focussed on the paramagnetically shifted resonances in the cyanoferric state of these chains. Two resonance peaks of the heme methyls are easily observable, together with several single proton peaks in the downfield region. The strong peaks in the high-field region are due to two methyl resonances of some amino-acid residue near the periphery of the heme, shifted up-field by the pseudocontact interaction. Effects of pH and of a modification of the protein on those resonances are presented. The exchangeable NH protons of the ring and of the peptide of the proximal histidine have resonance positions very similar to those in cyanoferric myoglobin, although the methyl resonances of the heme group are at somewhat different positions.