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Interpretation of the low-angle meridional neutron diffraction patterns from collagen fibres in terms of the amino acid sequence

1980; Elsevier BV; Volume: 2; Issue: 6 Linguagem: Inglês

10.1016/0141-8130(80)90015-x

1879-0003

David Hulmes, A. Miller, Stephen W. White, Peter A. Timmins, Carment Berthet-Colominas,

Machine Learning in Materials Science

Measurement of fully corrected, low angle meridional neutron diffraction intensities from native collagen fibres, in a full range of H2O/D2O contrasts, is described. The observed contrast dependence of the intensities of the first 12 orders of 670 A (D) axial periodicity is fitted to a general quadratic theory of contrast variation. The observed first order contrast dependence is compared to predictions based on the amino acid sequence, assuming different extents of chemical H/D exchange, and found to be consistent with complete non-carbon linked H/D exchange except for 1 to 1.6 hydrogen atoms per gly-X-Ytriplet involved in H-bonding. Both X-ray and neutron diffraction data in a variety of contrasts are consistent with a unique model for the axially projected structure of native collagen fibrils based on the amino acid sequence. This model if characterized by average axial residua translations in the NH2 and COOH terminal, non-triple helical telopeptides, expressed as multiples of the triple helical residue translation, of 0.85 ± 0.05 and 0.7 ± 01 respectively, with D = 235 ± 1 residues.