* It is determined primarily by local oxygen tension (paO2).
* It is affected by local tissue conditions (pH, temperature) and local concentrations of substances (2,3-diphosphoglycerate; 2,3-DPG).
* It produces an allosteric change in haemoglobin structure to a 'relaxed' form. In the absence of an allosteric effect a hyperbolic binding curve would result.
* It is 'co-operative', i.e. binding oxygen at each site promotes binding at the a remaining sites due to allosteric changes. An allosteric protein is one in which 3
o binding of a ligand to one site affects the binding properties of another site on O
the same protein. Haem-haem interaction and the interplay between oxygen n and the other four ligands are known collectively as the co-operative effects of haemoglobin.
* Deoxygenation of haemoglobin increases affinity of several proton-binding sites on its molecule.
Was this article helpful?