The involvement of tertiary conformational changes and the role of the alpha-chain-binding sites on oxygen-linked chloride release from human hemoglobin.
Chloride anions, when bound to human hemoglobin, lower the affinity for oxygen and increase the alkaline Bohr effect. These oxygen-linked characteristics are attributed to the preferential binding of Cl- to both alpha- and beta-chains in their deoxy configuration. It is demonstrated that the release of Cl- upon oxygenation is mainly due to tertiary changes, as shown by the effect of the anion on K1, the affinity constant of hemoglobin for oxygen at a very low saturation level (y less than or equal to 1.5%) where the cooperativity is unity. Investigation of the chloride effect on adult hemoglobin specifically carbamylated at the N-terminal valine of the alpha-chains, indicated a large inhibition of the effect of Cl-. The alpha-chain-binding sites appear to be the sites of the greatest affinity for the anion.
D001665:Binding Sites; D002712:Chlorides; D006441:Hemoglobin A; D006454:Hemoglobins; D006801:Humans; D010100:Oxygen; D011487:Protein Conformation
D002712:Chlorides; D006454:Hemoglobins; D006441:Hemoglobin A; D010100:Oxygen