Amyloid gels: precocious appearance of elastic properties during the formation of an insulin fibrillar network

The formation of insulin amyloid fibrils is important not only for the development of reliable drugs but also for modeling the basic properties of protein self-assembly. Fibrillation kinetics is typically characterized by an initial apparent lag phase related to the formation of oligomers, protofibrils, and aggregation nuclei. Afterwards, aggregation proceeds over a wide range of length scales via fibril elongation, thickening, and/or flocculation and eventual gelation. By light scattering and rheological techniques, we reveal the structural details hidden in the apparent lag phase and we show the unexpected appearance of noteworthy elastic properties concurrently with initial fibril nucleation and elongation preceding the formation of the larger structures and the gel network.