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 affect it. A variety of sample preparations were used; the iron chemical state was verified by Mossbauer 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 oxy- hemoglobin solutions to the presence of a small amount of the deoxy form.