Phase changes in sickle hemoglobin self-assembly

Sickle hemoglobin differs from normal adult hemoglobin by a single point mutation in two of its four subunits, and this renders it prone to self-assembly. This first-order phase transition generates stiff, 14-stranded fibers that are generated in dense arrays via a double-nucleation mechanism. The strands are only roughly equivalent, and they interact adhesively as well as obstructively to generate a solid in a process commonly referred to as gelation. This review will recount the essential features of this gelation process, as well as the successes of a mean-field approach to describing the interactions and kinetics of this first molecular disease.