We show that hen egg white lysozyme [HEWL] reproducibly forms amyloid fibrils in 80% ethanol at 22 degrees C with constant agitation. Fibril formation occurs over a time course of approximately 30 days, displays polymerization nucleation kinetics, and demonstrates a marked decrease in a-helical structure. Seeding with as little as 0.05% v/v of fibrils cleaved into smaller seed fragments by sonication abolishes the lag phase. Thioflavin T assays confirm the amyloid nature of the fibrils. Atomic force microscopy reveals unbranched amyloid fibrils with lengths varying between 1 and 3 m and heights ranging from 612 nm. The formation of amyloid fibrils in predominantly organic solvents demonstrates that the basic principles guiding fibril formation arise from interactions of the peptide backbone rather than from interactions between the amino acid side chains. (c) 2008 Elsevier Inc. All rights reserved.