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Effects of pH and ionic strength on the structure of collagen fibrils
Author(s) -
Ripamonti A.,
Roveri N.,
Braga D.,
Hulmes D. J. S.,
Miller A.,
Timmins P. A.
Publication year - 1980
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1980.360190503
Subject(s) - chemistry , ionic strength , neutron diffraction , crystallography , fiber diffraction , diffraction , fibril , neutron scattering , swelling , molecule , x ray crystallography , scattering , crystal structure , chemical engineering , optics , aqueous solution , organic chemistry , biochemistry , physics , engineering
The roles of pH and ionic strength on the structure and stability of collagen fibrils have been investigated by means of x‐ray and neutron diffraction techniques. High‐angle x‐ray diffraction shows that a salt concentration of 0.5 M KCl is sufficient to reduce the osmotic swelling and related disordering in the pH range 1–3. The relative intensities of the low‐angle meridional x‐ray and neutron diffraction Bragg reflections vary with pH. Difference Fourier syntheses between pH 7 and 1.6 data indicate, for both x‐ray and neutron diffraction, a reduced scattering contribution from the telopeptides at low pH. Lyotropic relaxation is a crucial step in the appearance at low pH of a doubling of the 668‐Å axial periodicity ( D ) of collagen fibrils. These results suggest that electrostatic interactions are essential for the structural stability of the telopeptide regions and of the 1 D and 3 D intermolecular staggers between collagen molecules.