Fibrillar structures of proteins play essential roles in normal life events as well as diseases. It is of great importance to understand the principles by which proteins organize into fibrils. Here, we report a rationally designed α-helical peptide that can aggregate into fibrils. Mutation studies indicate that the helicity of the peptide is crucial for fibril formation. Multiscale molecular dynamics simulations demonstrated that the peptide may assemble in a quasiregular pattern, which is different from both the coiled coil and cross-α structures reported before. Our study provides a new helical peptide design that produces a fibrillar structure and contributes to the understanding of fibrillar structures fo... More