Peptide Self-Assembly: Pathological Amyloid to Engineered Biomaterials The self-assembly of peptides and proteins into cross-β amyloid structures is a defining characteristic of amyloid pathologies including Alzheimers disease, Parkinsons disease, type 2 diabetes, and prion encephalopathies. Amyloid protein assemblies are not limited to pathological conditions, but also exist as evolutionarily conserved motifs with defined biological function.