title: Tensile mechanical properties of collagen type I and its enzymatic crosslinks.
abstract: Collagen type I crosslink type and prevalence can be influenced by age, tissue type, and health; however, the role that crosslink chemical structure plays in mechanical behavior is not clear. Molecular dynamics simulations of ~65-nm-long microfibril units were used to predict how difunctional (deH-HLNL and HLKNL) and trifunctional (HHL and PYD) crosslinks respond to mechanical deformation. Low- and high-strain stress-strain regions were observed, corresponding to crosslink alignment. The high-strain elastic moduli were 37.7, 37.9, 39.9, and 42.4GPa for the HLKNL, deH-HLNL, HHL, and PYD-crosslinked models, respectively. Bond dissociation analysis suggests that PYD is more brittle than HHL, with deH-HLNL and HLKNL being similarly ductile. These results agree with the tissues in which these crosslinks are found (e.g., deH-HLNL/HLKNL in developing tissues, HHL in mature skin, and PYD in mature bone). Chemical structure-function relationships identified for these crosslinks can aid the development of larger-scale models of collagenous tissues and materials.
authors.affiliation: Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA 24061, USA; Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA 24061, USA. Electronic address: alkwansa@vt.edu.
authors.forename: Albert L
authors.initials: AL
authors.lastname: Kwansa
authors.affiliation: Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA 24061, USA.
authors.forename: Raffaella
authors.initials: R
authors.lastname: De Vita
authors.affiliation: Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA 24061, USA; Department of Biomedical Engineering, Rutgers University, Piscataway, NJ 08854, USA. Electronic address: joseph.freeman@rutgers.edu.
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Freeman
mesh_terms: D000596:Amino Acids; D001842:Bone and Bones / Q000502:physiology; D024042:Collagen Type I / Q000737:chemistry*; D003432:Cross-Linking Reagents; D004151:Dipeptides; D055119:Elastic Modulus; D004798:Enzymes; D006801:Humans; D020894:Microfibrils / Q000737:chemistry; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D012879:Skin Physiological Phenomena; D013329:Structure-Activity Relationship; D013718:Tensile Strength
chemical_list: D000596:Amino Acids; D024042:Collagen Type I; D003432:Cross-Linking Reagents; D004151:Dipeptides; D004798:Enzymes; C010991:delta-hydroxylysylnorleucine; C015484:pyridinoline
keywords: Enzyme-derived crosslink; Microfibril; Molecular dynamics; Type I collagen