title: Mechanically overloading collagen fibrils uncoils collagen molecules, placing them in a stable, denatured state.
abstract: Due to the high occurrence rate of overextension injuries to tendons and ligaments, it is important to understand the fundamental mechanisms of damage to these tissues' primary load-bearing elements: collagen fibrils and their constituent molecules. Based on our recent observations of a new subrupture, overload-induced mode of fibril disruption that we call discrete plasticity, we have sought in the current study to re-explore whether the tensile overload of collagen fibrils can alter the helical conformation of collagen molecules. In order to accomplish this, we have analyzed the conformation of collagen molecules within repeatedly overloaded tendons in relation to their undamaged matched-pair controls using both differential scanning calorimetry and variable temperature trypsin digestion susceptibility. We find that tensile overload reduces the specific enthalpy of denaturation of tendons, and increases their susceptibility to trypsin digestion, even when the digestion is carried out at temperatures as low as 4 °C. Our results indicate that the tensile overload of collagen fibrils can uncoil the helix of collagen molecules, placing them in a stable, denatured state.
authors.affiliation: Division of Engineering, Saint Mary's University, Halifax, Canada. Electronic address: sam.veres@smu.ca.
authors.forename: Samuel P
authors.initials: SP
authors.lastname: Veres
authors.affiliation: School of Biomedical Engineering, Dalhousie University, Halifax, Canada.
authors.forename: Julia M
authors.initials: JM
authors.lastname: Harrison
authors.affiliation: School of Biomedical Engineering, Dalhousie University, Halifax, Canada; Department of Applied Oral Sciences, Dalhousie University, Halifax, Canada.
authors.forename: J Michael
authors.initials: JM
authors.lastname: Lee
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D024022:Fibrillar Collagens / Q000737:chemistry / Q000502:physiology*; D007700:Kinetics; D008297:Male; D011489:Protein Denaturation; D055550:Protein Stability; D020836:Protein Structure, Quaternary; D059748:Proteolysis; D012995:Solubility; D013710:Tendons / Q000737:chemistry / Q000502:physiology; D044366:Transition Temperature; D014357:Trypsin / Q000737:chemistry
chemical_list: D024022:Fibrillar Collagens; D014357:Trypsin
keywords: Collagen fibril; Denaturation; Differential scanning calorimetry; Discrete plasticity; Mechanical overload; Tendon