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Spectroscopy
Volume 18 (2004), Issue 1, Pages 1-11
http://dx.doi.org/10.1155/2004/932427

α and β Conformational preferences in fibril forming peptides characterised using NMR and CD techniques

Thelma A. Pertinhez,1,2 Amanda K. Sherwood,1 Leonardo F. Fraceto,3 Mario Bouchard,1 Maureen Pitkeathly,1 and Lorna J. Smith1

1Oxford Centre for Molecular Sciences, Central Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QH, UK
2Center for Molecular and Structural Biology, LNLS, CP 6192, 13084-971, Campinas, Brazil
3LNLS and Department of Biochemistry, University of Campinas, Campinas, Brazil

Copyright © 2004 Hindawi Publishing Corporation. 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.

Abstract

Peptide fragments taken from residues 18‒54 of short consensus repeat 3 (SCR3) from the human complement receptor CR1 have been found in aqueous solution to slowly aggregate and form fibrils. NMR studies of the monomeric form of these peptides show that they are essentially unfolded in aqueous solution and that they all have an increased helicity in TFE solutions. The behaviour of residues 28‒31 from SCR3 is particularly interesting. These residues have a high β-sheet propensity in the native protein and a seven peptide containing their sequence is found to form fibrils despite its short length. However, NMR studies show that these residues adopt a well-defined α-helix in 80% TFE and under these conditions fibril formation has not been observed. These data demonstrate the strong dependence of conformational propensities on environment.