Magnetic susceptibility of oxy- and carbonmonoxyhemoglobins.

The room temperature magnetic susceptibilities of human and carp oxy- and carbonmonoxyhemoglobin solutions were measured in a 30-gauss (1 G = 10(-4) T) field with a superconducting magnetometer. To within experimental uncertainty, the susceptibility was the same for both the oxy and carbonmonoxy forms, and salt concentration did not effect it. A variety of sample preparations were used; the iron chemical state was verified by Mössbauer spectroscopy. A value of -0.580 +/- 0.010 X 10(-6) centimeter-gram-second (cgs) system was obtained for the mass susceptibility of the protein. We attribute the paramagnetism sometimes observed in oxyhemoglobin solutions to the presence of a small amount of the deoxy form.