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Abstract (Expand)
Collagen is a force-bearing, hierarchical structural protein important to all connective tissue. In tendon collagen, high load even below macroscopic failure level creates mechanoradicals by homolytic … bond scission, similar to polymers. The location and type of initial rupture sites critically decide on both the mechanical and chemical impact of these micro-ruptures on the tissue, but are yet to be explored. We here use scale-bridging simulations supported by gel electrophoresis and mass spectrometry to determine breakage points in collagen. We find collagen crosslinks, as opposed to the backbone, to harbor the weakest bonds, with one particular bond in trivalent crosslinks as the most dominant rupture site. We identify this bond as sacrificial, rupturing prior to other bonds while maintaining the material’s integrity. Also, collagen’s weak bonds funnel ruptures such that the potentially harmful mechanoradicals are readily stabilized. Our results suggest this unique failure mode of collagen to be tailored towards combatting an early onset of macroscopic failure and material ageing.
Authors: Benedikt Rennekamp, Christoph Karfusehr, Markus Kurth, Aysecan Ünal, Kai Riedmiller, Ganna Gryn’ova, David M. Hudson, Frauke Gräter
Date Published: 12th Apr 2023
Publication Type: Journal
DOI: 10.1038/s41467-023-37726-z
Citation: Nat Commun 14, 2075 (2023).
Created: 21st Oct 2022 at 17:53, Last updated: 14th Apr 2023 at 06:38
Abstract (Expand)
Here we uncover collagen, the main structural protein of all connective tissues, as a redox-active material. We identify dihydroxyphenylalanine (DOPA) residues, post-translational oxidation products … of tyrosine residues, to be common in collagen derived from different connective tissues. We observe that these DOPA residues endow collagen with substantial radical scavenging capacity. When reducing radicals, DOPA residues work as redox relay: they convert to the quinone and generate hydrogen peroxide. In this dual function, DOPA outcompetes its amino acid precursors and ascorbic acid. Our results establish DOPA residues as redox-active side chains of collagens, probably protecting connective tissues against radicals formed under mechanical stress and/or inflammation.
Authors: Markus Kurth, Uladzimir Barayeu, Hassan Gharibi, Andrei Kuzhelev, Kai Riedmiller, Jennifer Zilke, Kasimir Noack, Vasyl Denysenkov, Reinhard Kappl, Thomas F. Prisner, Roman A. Zubarev, Tobias P. Dick, Frauke Gräter
Date Published: 3rd Apr 2023
Publication Type: Journal
Citation: Angew. Chem. Int. Ed. 2023, e202216610
Created: 24th Jan 2023 at 08:31, Last updated: 4th Apr 2023 at 09:54