Sodium fusidate prevents protein aggregation of silk fibroin and offers new perspectives for human lens material disaggregation.

Silk fibroin (SF) is a non-pathological amyloidogenic protein prone, in solution, to the formation of amyloid-like aggregated species, displaying similarities in fibrillation kinetics with pathological amyloids, as widely reported in the literature. We show here, on the basis of different biophysical approaches (turbidity, Congo Red assays, CD, DLS and fluorescence), that fusidic acid (FA), a well-known antibiotic, acts on SF as an anti-aggregating agent in a dose-dependent manner, being also able to revert SF aggregation. FA binds to SF inducing changes in the environment of SF aromatic residues.

ANS fluorescence: Potential to discriminate hydrophobic sites of proteins in solid states.

In the current study, ANS fluorescence was established as a powerful tool to study proteins in solid-state. Silk fibroin from cocoons was used as a paradigm protein. ANS incorporated into the films of silk fibroin exhibits fluorescence with two-lifetime components that can be assigned to the patches and/or cavities with distinct hydrophobicities.

Rhodamine binds to silk fibroin and inhibits its self-aggregation.

Amyloid structures are universal structures, widely diffuse in nature. Silk, capable of forming some of the strongest tensile materials on earth represents an important example of formation of functional amyloid fibrils, a process reminiscent of the oligomerization of peptides involved in neurodegenerative diseases. The stability of silk fibroin solutions in different conditions and its transition from α-helix/random coil to β-sheet structures, at the basis of gelation processes and fibril formation, have been here investigated and monitored employing different biophysical approaches.