Amyloid hydrogel derived from curly protein fibrils of α-synuclein

Elucidation of molecular assembly mechanism of protein-based suprastructure formation is pivotal to develop biomaterials. A single amyloidogenic protein of α-synuclein turned into two morphologically distinctive amyloid fibrils – ‘curly’ (CAF) vs. ‘straight’ (SAF) – depending on its fibrillation processes. Mutually exclusive production of CAF and SAF was achieved with either centrifugal membrane filtration of the preformed oligomeric species of α-synuclein or agitated incubation of its monomeric form, representing amyloidogeneses via double-concerted and nucleation-dependent fibrillation model, respectively. Differences in secondary structures of CAF and SAF have been suggested to be responsible for their morphological uniqueness with structural flexibility and mechanical strength. Both polymorphs exerted the self-propagation property, demonstrating that their characteristic morphologies were inherited for two consecutive generations to daughter and granddaughter fibrils through the seed-dependent fibrillation procedure. Accumulation of CAF produced amyloid hydrogel composed of fine nano-scaled three-dimensional protein fibrillar network. The hydrogel made of daughter CAF was demonstrated to be a suitable nanomatrix for enzyme entrapment, which protected the entrapped enzyme of horseradish peroxidase from loss of activity due to multiple catalyses and heat treatment. The nano-scaled fibrillar network of CAF, therefore, could exhibit a full potential to be further applied in the promising areas of nanobiotechnology including tissue engineering, drug delivery, nanofiltration and biosensor development.