Magnetic-field-dependent water proton spin-lattice relaxation rates of hemoglobin solutions and whole blood

Abstract

The spin-lattice relaxation rates of solvent water protons in solutions of normal and sickle cell hemoglobin, normal red blood cells, and whole blood have been measured at magnetic fields between 5 Oe and 12 kOe. The field-dependent data have been analyzed to obtain the rotational tumbling time of the hemoglobin molecules and a measure of water-protein interaction. Comparison of the protein tumbling time in concentrated hemoglobin solutions to the tumbling time of hemoglobin inside red blood cells indicates that encapsulation of hemoglobin within the cell membrane has little effect on its molecular motion. The relaxation rates of solutions of deoxygenated sickle cell hemoglobin indicate that when the solution forms a gel at 10°C, approximately 90% of the hemoglobin molecules remain in solution and are freely tumbling, but at 35°C, virtually all of the hemoglobin has been incorporated into the gel structure. © 1974.