Hb Montfermeil [beta 130(H8) Tyr-->Cys]: suggests a key role for the interaction between helix A and H in oxygen affinity of the hemoglobin molecule

Hb Montfermeil [beta130(H8) Tyr-->Cys] is a high oxygen affinity variant causing erythrocytosis. The cysteine replacement is buried in the inside of the beta chain where it alters the interactions between helix A and H, with a further effect on helix E. This position has already been proposed to contribute to the difference in oxygen affinity between human and bovine hemoglobins. Three dimensional structural considerations and comparison of the functional behavior of other variants suggest that this region is an important determinant of the intrinsic oxygen affinity of the hemoglobin molecule.