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X-ray diffraction study into the effects of liming on the structure of collagen.

Maxwell CA, Wess TJ, Kennedy CJ

Biophysics Division, School of Optometry and Vision Sciences, University of Cardiff, Redwood Building, King Edward VII Avenue, Cathays Park, Cardiff, Wales, United Kingdom. MaxwellCA@cardiff.ac.uk

The manufacture of parchment from animal skin involves processes that remove hair, fats, and other macromolecules. Although it is well understood that the collagen fibers "open up" during processing, this study uses small and wide-angle X-ray diffraction to measure quantitatively the changes induced at the nanoscopic and microscopic levels. The axial rise per residue distance within the collagen molecules is unaffected by salt and lime treatments. Salting of the hides appears to remove noncollagenous materials. The intermolecular lateral packing distance between the hydrated collagen molecules (1.4 nm) increases after salting ( approximately 1.5 nm) and liming ( approximately 1.55 nm); drying is responsible for a reduction to approximately 1.2 nm in all samples. The axial staggered array (d spacing) is reduced by 1 nm after liming and is unaffected by drying. The average fibril diameter increases from 103.2 to 114.5 nm following liming, and the fibril-to-fibril distance increases from 122.6 to 136.1 nm.

Published 14 August 2006 in Biomacromolecules, 7(8): 2321-6.
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