Heme orientational heterogeneity in deuterohemin-reconstituted horse and human hemoglobin characterized by proton nuclear magnetic resonance spectroscopy

The number of 2,4-H signals of met-cyano and deoxy deuteroheme-reconstituted sperm whale Mb are shown to reflect the known degree of heme rotational disorder in this modified protein. Using these unique spectral windows for the 2,4-H signals, we show that both horse and human Hb reconstituted with deuteroheme exhibit significant molecular heterogeneity which is consistent with approximately 20% heme rotational disorder within each subunit.