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Lookup NU author(s): Professor Robin Harris, Professor Rick Lewis
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).
The collagen type I segment long spacing (SLS) crystallite is a well-ordered rod-like molecular aggregate, similar to 300 nm in length, which is produced in vitro under mildly acidic conditions (pH 2.5-3.5) in the presence of 1 mM ATP. The formation of the SLS crystallite amplifies the inherent linear structural features of individual collagen heterotrimers, due to the punctate linear distribution and summation of the bulkier amino acid side chains along the length of individual collagen heterotrimers. This can be correlated structurally with the 67 nm D-banded collagen fibril that is found in vivo, and formed in vitro. Although first described many years ago, the range of conditions required for ATP-induced SLS crystallite formation from acid-soluble collagen have not been explored extensively. Consequently, we have addressed biochemical parameters such as the ATP concentration, pH, speed of formation and stability so as to provide a more complete structural understanding of the SLS crystallite. Treatment of collagen type I with 1 mM ATP at neutral and higher pH (6.0-9.0) also induced the formation of D-banded fibrils. Contrary to previous studies, we have shown that the polysulphonated diazo dyes Direct red (Sirius red) and Evans blue, but not Congo red and Methyl blue, can also induce the formation of SLS-like aggregates of collagen, but under markedly different ionic conditions to those employed in the presence of ATP. Specifically, pre-formed D-banded collagen fibrils, prepared in a higher than the usual physiological NaCl concentration (e.g. 500 mM NaCl, 20 mM Tris-HCl pH7.4 or x3 PBS), readily form SLS aggregates when treated with 0.1 mM Direct red and Evans blue, but this did not occur at lower NaCl concentrations. These new data are discussed in relation to the anion (Cl-) and polyanion (phosphate and sulphonate) binding by the collagen heterotrimer and their likely role in collagen fibrillogenesis and SLS formation. (C) 2016 Elsevier Ltd. All rights reserved.
Author(s): Harris JR, Lewis RJ
Publication type: Article
Publication status: Published
Journal: Micron
Year: 2016
Volume: 86
Pages: 36-47
Print publication date: 01/07/2016
Online publication date: 28/04/2016
Acceptance date: 27/04/2016
Date deposited: 13/07/2016
ISSN (print): 0968-4328
ISSN (electronic): 1878-4291
Publisher: Elsevier
URL: http://dx.doi.org/10.1016/j.micron.2016.04.008
DOI: 10.1016/j.micron.2016.04.008
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