Protonation States of Buried Histidine Residues in Human Deoxyhemoglobin Revealed by Neutron Crystallography

摘要

Human hemoglobin (Hb),an α_2β_2 tetrameric hemoprotein arranged as a dimer of identical αβ dimers, has evolved to allow efficient transport of oxygen from the lungs to tissues. Perhaps the most remarkable property of Hb is cooperativity that is generally explained as the result of a shift in the equilibrium between the two quaternary structures from the low-affinity T (tense) state to the high-affinity R (relaxed) state during oxygenation.