Within one year, Pauling, in collaboration with research fellow Charles D. Coryell, wrote two articles on the magnetic properties and structure of hemoglobin and its derivatives. One paper dealt with the question of how oxygen and carbon monoxide bind to hemoglobin. In order to answer this question, Pauling devised a new approach for examining hemoglobin – through its magnetic properties. Pauling and Coryell found that oxyhemoglobin and carbonmonoxyhemoglobin have no magnetic moment and therefore all electrons are paired. In comparison, hemoglobin exhibits paramagnetism, meaning that hemoglobin has unpaired electrons. Specifically, Pauling and Coryell stated that each heme has four unpaired electrons. Thus, they determined that the iron in hemoglobin forms ionic (not covalent) bonds with nitrogen and the globin, while oxyhemoglobin and carbonmonoxyhemoglobin form covalent bonds at the same locations. They remarked: "It is interesting and surprising that the hemoglobin molecule undergoes such an extreme structural change on the addition of oxygen or carbon monoxide." According to Pauling and Coryell, the formation of covalent bonds (rather than ionic bonds) most likely explained why hemoglobin bonded more readily with oxygen and carbon monoxide than with other substances. Pauling reflected in 1970 upon the importance of his work with Coryell: "These studies of the magnetic properties of hemoglobin and its compounds led to a great increase in understanding of the structure of the hemoglobin molecule in the neighborhood of the heme groups."
Source. Just to point out, though, a 1.3 Tesla field is a hell of a powerful magnetic field. Immersing an entire body in a field of that strength requires superconducting solenoids. Big bucks.
Also makes me wonder: is oxygenated blood a contrast agent for MRI scans?
Good question! It could show places of poor circulation!...............