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Biochemistry Research International
Volume 2011, Article ID 198325, 10 pages
Research Article

The Molecular Architecture for the Intermediate Filaments of Hard α-Keratin Based on the Superlattice Data Obtained from a Study of Mammals Using Synchrotron Fibre Diffraction

Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia

Received 19 May 2011; Revised 23 August 2011; Accepted 23 August 2011

Academic Editor: Trevor Creamer

Copyright © 2011 Veronica James. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


High- and low-angle X-ray diffraction studies of hard α-keratin have been studied, and various models have been proposed over the last 70 years. Most of these studies have been confined to one or two forms of alpha keratin. This high- and low-angle synchrotron fibre diffraction study extends the study to cover all available data for all known forms of hard α-keratin including hairs, fingernails, hooves, horn, and quills from mammals, marsupials, and a monotreme, and it confirms that the model proposed is universally acceptable for all mammals. A complete Bragg analysis of the meridional diffraction patterns, including multiple-time exposures to verify any weak reflections, verified the existence of a superlattice consisting of two infinite lattices and three finite lattices. An analysis of the equatorial patterns establishes the radii of the oligomeric levels of dimers, tetramers, and intermediate filaments (IFs) together with the centre to centre distance for the IFs, thus confirming the proposed helices within helices molecular architecture for hard α-keratin. The results verify that the structure proposed by Feughelman and James meets the criteria for a valid α-keratin structure.