Interaction of hemoglobin with chloride and 2,3‐bisphosphoglycerate

• Published in: European Journal of Biochemistry
• Main Authors: GIARDINA, Bruno, BRIX, Ole, COLOSIMO, Alfredo, PETRUZZELLI, Raffaele, CERRONI, Loredana, CONDO, Saverio G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1990
• Subjects: musk ox; Rangifer tarandus
• Online Access: http://dx.doi.org/10.1111/j.1432-1033.1990.tb19427.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1432-1033.1990.tb19427.x; https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1990.tb19427.x

The equilibrium oxygen‐binding properties of hemoglobins from reindeer ( Rangifer tarandus tarandus ), musk ox ( Ovibos muschatos ) and a bat ( Rousettus aegyptiacus ) have been investigated with special reference to the effect of heterotrophic ligands such as chloride and 2,3‐bisphosphoglycerate [Gri(2,3) P 2 ]. The results obtained with hemoglobins from reindeer and musk ox indicate that their low oxygen affinity and their insensitivity to Gri(2,3) P 2 are not only an intrinsic property of the molecule, as proposed in the case of ruminant hemoglobins, but also the results of the interplay between chloride and Gri(2,3) P 2 interactions. In other words, insensitivity of reindeer and musk ox hemoglobins to Gri(2,3) P 2 is mainly due to a decreased affinity constant for this cofactor and to an increased affinity constant for chloride anions; this renders more effective the competition of chloride for the anion‐binding site. On the other hand bat hemoglobin behaves in a completely different way and could be regarded as a type case of low‐affinity hemoglobin since its functional properties are modulated neither by chloride nor by Gri(2,3) P 2 . The results are discussed in the light of the amino acid residues which are known to be involved in the binding of organic phosphates.