Observation of the Dissociation of Unliganded Hemoglobin

摘要: Abstract A method is described for determining the equilibrium constant of tetramer-dimer dissociation reaction unliganded hemoglobin. The based on large difference between ligand binding affinities dimer and tetramer, utilizes affinity dilute hemoglobin solutions as a sensitive assay fraction heme in dimeric state. CO containing 0.05 to 8.0 µm have been determined, show dependence concentration expected equilibrium. In 0.1 m phosphate, pH 7.0, this by 3 x 10-12 m. Experiments with 2.0 NaCl, indicate an increase 7 10-11 amount tetramer present these combined capacity generate cooperativity accounts quantitatively highly cooperative (Hill's constant, n = 2.3). addition, ratio constants liganded yields value allosteric L. This 6.7 105, which good agreement earlier estimates