A particularly useful system to investigate such relationships is lysozyme, a protein with four disulfide bonds that is well characterized23,24 and forms amyloid deposits in patients suffering from familial lysozyme systemic amyloidosis,25 a disease that occurs when amyloidogenic mutations in the protein lead to the formation of partially unfolded amyloidogenic intermediates.23,26,27 By incubating lysozyme under various destabilizing conditions, we have produced fibrils differing in morphology, molecular structure, stability, and cytotoxicity. Here, LYZ is linked to primary systemic amyloidosis.