title: quantitative determination of collagen cross-links.
abstract: The primary functional role of collagen is as a supporting tissue and it is now established that the aggregated forms of the collagen monomers are stabilised to provide mechanical strength by a series of intermolecular cross-links. In order to understand the mechanical properties of collagen, it is necessary to identify and quantitatively determine the concentration of the cross-links during their changes with maturation, ageing and disease. These cross-links are formed by oxidative deamination of the epsilon-amino group of the single lysine or hydroxylysine in the amino and carboxy telopeptides of collagen by lysyl oxidase, the aldehyde formed reacting with a specific lysine or hydroxylysine in the triple helix. The divalent Schiff base and keto-amine bonds so formed link the molecules head to tail and spontaneously convert during maturation to trivalent cross-links, a histidine derivative and cyclic pyridinolines and pyrroles, respectively. These latter bonds are believed to be transverse inter-fibrillar cross-links, and are tissue rather than species specific. We describe the determination of these cross-links in detail.Elastin is also stabilised by cross-linking based on oxidative deamination of most of its lysine residues to yield tetravalent cross-links, desmosine and iso-desmosine, the determination of which is also described.A second cross-linking pathway occurs during ageing (and to a greater extent in diabetes mellitus) involving reaction with tissue glucose. The initial product glucitol-lysine can be determined as furosine and pyridosine, and determination of advanced glycation end-products believed to be cross-links, such as pentosidine, are also described.
authors.affiliation: University of Bristol, Langford, Bristol, UK.
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Avery
authors.forename: Trevor J
authors.initials: TJ
authors.lastname: Sims
authors.forename: Allen J
authors.initials: AJ
authors.lastname: Bailey
mesh_terms: D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003094:Collagen / Q000737:chemistry*; D005947:Glucose / Q000737:chemistry; D006868:Hydrolysis; D011758:Pyrroles / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D011758:Pyrroles; D003094:Collagen; D005947:Glucose