A proton magnetic relaxation study of ferric myoglobin and haemoglobin in water/ethanediol solutions.
Structural alterations of the haem vicinity of the high-spin derivatives of bovine ferric myoglobin (metmyoglobin) and human haemoglobin and the changes of the interaction with inositol hexaphosphate induced by ethanediol were monitored by solvent-proton magnetic relaxation. On addition of ethanediol up to 60% the fluoromet derivatives exhibit a gradual increase in the accessibility of the haem for the molecules from the solvent. In aquomethaemoglobin solutions with more than 25% ethanediol there is no unique explanation of proton magnetic relaxation. Ethanediol enhances the  binding of inositol hexaphosphate to methaemoglobin, but the structural consequences of this binding on the haem-pockets seem to be diminished. The mechanisms of the observed structural and functional alterations of myoglobin as well as haemoglobin tetramer are discussed here.
D000818:Animals; D002417:Cattle; D005026:Ethylene Glycols; D006418:Heme; D006454:Hemoglobins; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007501:Iron; D009682:Magnetic Resonance Spectroscopy; D008706:Methemoglobin; D009211:Myoglobin; D011487:Protein Conformation; D013696:Temperature
D005026:Ethylene Glycols; D006454:Hemoglobins; D009211:Myoglobin; D006418:Heme; D008706:Methemoglobin; D007501:Iron