Structure of amyloid fibrils of hen egg white lysozyme studied by microbeam X-ray diffraction.

Structure of spherical aggregates formed by hen egg white lysozyme (HEWL) was studied with microbeam X-ray diffraction. Aggregates with a diameter of 50-100 microm were formed after incubation of HEWL at pH 1.6 and 60 degrees C up to 60 days. The scattering from the aggregate in solution showed a marked symmetry demonstrating it as a spherulite. A reflection at 1/0.46 nm(-1) along the fiber axis showed the presence of beta-sheets along the fiber. There were strong equatorial reflections at 1/2.4 and 1/1.2 nm(-1). The similarities to other amyloid fibers suggest that molecules are planar in the direction perpendicular to the fiber axis and beta-strands are making hydrogen bonds to neighboring molecules.