title: The structure of the alpha-keratin microfibril.
abstract: Quantitative measurements of the intensity of the meridional reflections in the X-ray-diffraction pattern of alpha-keratin are shown to be consistent with a microfibril structure in which a surface lattice with an axially projected period around 200 A is subject to a periodic interruption with an axially projected period of 470 A. Taken in conjunction with recent evidence on the chemical structure of alpha-keratin and other intermediate filaments this finding enables an elaboration to be made of a model proposed earlier by RDB Fraser, TP MacRae, & E Suzuki (J. Mol. Biol. 108, 435-452, 1976) for the alpha-helical framework of the microfibril. The disposition and connectivity of the helical segments suggested here provides a straightforward explanation of a number of recent physicochemical and electron-microscopical observations on intermediate filaments and provides a starting point for the development of models for the framework of other intermediate filaments.
authors.affiliation: Division of Protein Chemistry, CSIRO, Parkville, Victoria, Australia.
authors.forename: R D
authors.initials: RD
authors.lastname: Fraser
authors.forename: T P
authors.initials: TP
authors.lastname: MacRae
mesh_terms: D007633:Keratins / Q000737:chemistry*; D020894:Microfibrils / Q000737:chemistry*; D008961:Models, Structural; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D014961:X-Ray Diffraction
chemical_list: D007633:Keratins