Non-synergistic interactions between strong allosteric effectors and human embryonic and adult haemoglobins.

The binding of two strong allosteric effectors (2,3 Diphosphoglycerate D.P.G., and Bezafibrate, Bzf) to both adult and the three human embryonic haemoglobins, either individually or in combination, have been studied in detail. The adult protein exhibits one binding site for D.P.G and two for Bzf. When both effectors are present simultaneously their effects are simply additive. The same qualitative pattern of binding is observed in the case of the three human embryonic haemoglobins, although with different binding constants. The lack of synergism between these effectors and the different binding affinity expressed by these proteins are discussed in terms of the known amino acid sequence differences.