title: Intact Telopeptides Enhance Interactions between Collagens.
abstract: Collagen is the fundamental structural component of a wide range of connective tissues and of the extracellular matrix. It undergoes self-assembly from individual triple-helical proteins into well-ordered fibrils, a process that is key to tissue development and homeostasis, and to processes such as wound healing. Nucleation of this assembly is known to be slowed considerably by pepsin removal of short nonhelical regions that flank collagen's triple helix, known as telopeptides. Using optical tweezers to perform microrheology measurements, we explored the changes in viscoelasticity of solutions of collagen with and without intact telopeptides. Our experiments reveal that intact telopeptides contribute a significant frequency-dependent enhancement of the complex shear modulus. An analytical model of polymers associating to establish chemical equilibrium among higher-order species shows trends in G' and G″ consistent with our experimental observations, including a concentration-dependent crossover in G″/c around 300 Hz. This work suggests that telopeptides facilitate transient intermolecular interactions between collagen proteins, even in the acidic conditions used here.
authors.affiliation: Department of Chemistry, Simon Fraser University, Burnaby, Canada.
authors.forename: Marjan
authors.initials: M
authors.lastname: Shayegan
authors.affiliation: Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada; Department of Physics, Simon Fraser University, Burnaby, Canada.
authors.forename: Tuba
authors.initials: T
authors.lastname: Altindal
authors.affiliation: Department of Physics, Simon Fraser University, Burnaby, Canada.
authors.forename: Evan
authors.initials: E
authors.lastname: Kiefl
authors.affiliation: Department of Chemistry, Simon Fraser University, Burnaby, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada; Department of Physics, Simon Fraser University, Burnaby, Canada. Electronic address: nforde@sfu.ca.
authors.forename: Nancy R
authors.initials: NR
authors.lastname: Forde
mesh_terms: D000818:Animals; D024042:Collagen Type I / Q000737:chemistry* / Q000378:metabolism*; D004548:Elasticity; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D051381:Rats; D014783:Viscosity
chemical_list: D024042:Collagen Type I