ABSTRACT
Silks are a class of structural proteins produced by arthropods, which like amyloids are evolutionarily very ancient structures. Silk proteins are produced in special glands and are stored at high concentrations in solution known as dope until they are transformed into a solid silk thread. The processing conditions have a great influence on the protein structure and the mechanical properties of the final thread. Ancient cocoon silks (used for the preservation of offspring) display cross-β structures similar to amyloid fibrils. Spiders have evolved other silks for task-specific applications (such as the capture of prey or as a lifeline to escape from predators) with different mechanical properties. The spinning process evolved in parallel, becoming more complex. In contrast to ancient silks, more recent silks tend to display predominantly parallel-β structures, but under distinct processing conditions adopt amyloid-like structures.
