The Thermal Structural Transition of α-Crystallin Inhibits the Heat Induced Self-Aggregation

[Image: see text]-crystallin, the major constituent of human lens, is a member of the heat-shock proteins family and it is known to have a quaternary structural transition at [Image: see text]. The presence of calcium ions and/or temperature changes induce supramolecular self-aggregation, a process of relevance in the cataractogenesis. Here we investigate the potential effect of the bovine [Image: see text]-crystallin's structural transition on the self-aggregation process. Along all the temperatures investigated, aggregation proceeds by forming intermediate molecular assemblies that successively aggregate in clusters. The final morphology of the aggregates, above and below [Image: see text], is similar, but the aggregation kinetics are completely different. The size of the intermediate molecular assemblies, and their repulsive energy barrier show a marked increase while crossing [Image: see text]. Our results highlight the key role of heat modified form of [Image: see text]-crystallin in protecting from aggregation and preserving the transparency of the lens under hyperthermic conditions.