Open AccessInteraction of hemoglobin with chloride and 2,3‐bisphosphoglycerate
Author(s) -
GIARDINA Bruno,
BRIX Ole,
COLOSIMO Alfredo,
PETRUZZELLI Raffaele,
CERRONI Loredana,
CONDO Saverio G.
Publication year - 1990
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1990.tb19427.x
Subject(s) - chloride , hemoglobin , chemistry , oxygen , amino acid , biochemistry , organic chemistry
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.