Kinetics of the in vitro gelation of a sickling haemoglobin from Hog deer (Axis porcinus).

In order to distinguish the molecular mechanisms involved in the polymerisation of animal and human sickling haemoglobins, the gelation properties of hog deer (Axis porcinus) haemoglobin have been studied. Continuous monitoring of viscosity and minimum gelling concentration measurements of hog deer haemolysates were made over a range of pH, temperature, ionic strengths and in the presence of urea and tris(hydroxymethyl)methylamine. The inhibition of gelling caused by lowering the pH or increasing ionic strength and the abolition of the reversible endothermic nature of gelation by urea suggest that electrostatic interactions predominate in polymerisation but that weak hydrogen and hydrophobic bonds may also be present. Kinetic viscosity data demonstrated a pre-gelation lag phase, dependent on ahigh power of the haemoglobin concentration, similar to the nucleation of human haemoglobin S (HbS). The results indicate similarities in the kinetics of hog deer polymerisation with those of HbS, but major differences in the type of intermolecular attractions involved.