Amyloid formation by salmon calcitonin.

It is demonstrated using three independent methods that salmon calcitonin can form amyloid fibrils in vitro. Large aggregates are shown to exhibit a blue-green birefringence in cross polarised light after staining with congo red. Individual fibrils were observed using electron microscopy. These fibrils are approx. 50-60 A in diameter and up to 20,000 A in length and are similar in appearance to those observed in Alzheimer's disease. Finally, X-ray diffraction studies of the large aggregates reveal the cross-beta conformation characteristics of the monomers in the fibre.