Increased oxygen affinity with normal heterotropic effects in hemoglobin Loire [α88(F9)Ala→Ser]

Abstract

Increased homotropic allosteric effect, while maintaining normal heterotropic effects, was observed in hemoglobin Loire. The oxygen binding curves, at equilibrium, and the kinetic measurements demonstrated that the substitution of alpha 88(F9) Ala for a Ser results in increased oxygen affinity and decreased n50 value. The function of the residues involved in the Bohr effect or in the regulation by 2,3-bisphosphoglycerate is not altered. The effects of bezafibrate, which binds specifically to the alpha chains, was similar to that observed in Hb A. The functional properties of Hb Loire may be explained by a slight displacement of some key residues of the C-terminal region of the alpha chain destabilizing the T structure.