title: NMR relaxation of protein and water protons in methemoglobin solutions.
abstract: Hemoglobin (Hb) proton spins rapidly equilibrate among themselves after an initial excitation, and relax toward thermal equilibrium as a unit. In the diamagnetic form, spin diffusion to nearby methyl relaxation sinks can account for this. For metHb, four strong heme relaxation centers dominate, and spin diffusion must occur over long distances. A sizeable difference in protein T1 is found between H2O and D2O solutions, much more than for diamagnetic Hb, consistent with internal H2O acting as a spin carrier to the heme.
mesh_terms: D006418:Heme; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008433:Mathematics; D008706:Methemoglobin; D011487:Protein Conformation; D012996:Solutions; D014867:Water
chemical_list: D012996:Solutions; D014867:Water; D006418:Heme; D008706:Methemoglobin