The effect of non-aggregating proteins upon the gelation of sickle cell hemoglobin: model calculations and data analysis.

The scaled particle theory for mixtures of hard spheres is used to calculate the effect of added proteins of varying size upon the solubility of sickle cell hemoglobin. For a given added weight, smaller macromolecules are more effective in lowering the solubility of sickle cell hemoglobin. Calculations based upon this model agree with many recently reported observations. The observed effect of the addition of myoglobin or hemoglobin α-chains on the minimum gelling concentration of sickle cell hemoglobin (Benesch $\text{et al.}$), however, is smaller than predicted. We suggest that this difference may arise from self-association of the added species.