Abstract

Sickle cell haemoglobin polymerization reduces erythrocyte deformability, causing deleterous vaso-occlusions. The double-nucleation model states that polymers grow from HbS aggregates, the nuclei, in solution , onto existing polymers . When linearized at initial HbS concentration, this model predicts early polymerization and its characteristic delay-time :591–610, 611–631, 1985). Addressing its relevance for describing complete polymerization, we constructed the full, non-linearized model . Here, we compare the simulated outputs to experimental progress curves . Within 10% from start, average root mean square deviation between simulated and experimental curves is 0.04 ± 0.01 . Conversely, for complete progress curves, averaged rms is 0.48 ± 0.04. This figure is improved to 0.13 ± 0.01 by adjusting heterogeneous pathway parameters : the nucleus stability , and the fraction of polymer surface available for nucleation , from 5e−7, to 13 . Similar results are obtained at 37°C. We conclude that the physico-chemical description of heterogeneous nucleation warrants refinements in order to capture the whole HbS polymerization process