Organization of microfibrils in keratin fibers studied by X-ray scattering

The study presented a new model for analyzing low-angle X-ray equatorial scattering intensity profiles of hard alpha-keratin fibers, such as those found in human and horse hair and porcupine quills. The model incorporated three key components: the electron density profile of the microfibril, the distribution function of the microfibrils, and a background signal. A paracrystal distribution function was used to describe the microfibril arrangement within a hexagonal lattice, simplifying the analysis to two parameters. The study found that while the diameter of the microfibrils (7.4 nm) was consistent across different origins, the distances between microfibrils and their electron density profiles varied. This approach improved the understanding of keratin fiber structure and could be applied to other hexagonal fibrillar assemblies in biological tissues.