A new molecular model for collagen elasticity based on synchrotron X-ray scattering evidence

Abstract

Collagen is the most abundant structural protein in vertebrates. The specific shape of its stress-strain curve is crucial for the function of a number of organs. Although the macroscopic mechanical behavior of collagen is well known, there is still no explanation of the elastic process at the supramolecular level. We have performed in situ synchrotron x-ray scattering experiments, which show that the amount of lateral molecular order increases upon stretching of collagen fibers. In strain cycling experiments the relation between strain and diffuse equatorial scattering was found to be linear in the "heel" region of the stress-strain curve. A new molecular model for collagen elasticity is proposed, which, based on the existence of thermally activated molecular kinks, reproduces this linearity and gives a simple explanation for the form of the stress-strain curve of collagen.

A theoretical model for F-actin remodeling in vascular smooth muscle cells subjected to cyclic stretch

“…where the 1' (primed) coordinate axis coincides with the direction of a generic filament, and Consistent with previous reports that the mechanical behavior of individual CSK filaments is nonlinear and qualitatively similar to those of soft tissue (Janmey et al, 1991;Liu and Pollack 2002;Deguchi et al, 2006), two specific functional forms of the first Piola-Kirchhoff stressstretch relation (∂ w ∕ ∂ α k ) for individual stress fibers were compared (Humphrey and Yin, 1987;Misof et al, 1997):…”

Collagen from the osteogenesis imperfecta mouse model (oim) shows reduced resistance against tensile stress.

“…A small segment was dissected from each tendon and its diameter was measured with a calibrated eyepiece under a light microscope. The remaining part of each tendon was kept in PBS at room temperature to maintain it in a wet condition and mounted into the upper and lower grips of a self-made mechanical testing machine described previously (13).…”

Healing of subcutaneous tendons: Influence of the mechanical environment at the suture line on the healing process

“…The ability of tendons to stretch and recoil enables them to save energy in running by allowing the limb to have shorter muscle fascicles or slower muscle fibers that the tendon up to 2% of its length and the straightening of the macroscopic crimp in the collagen fibrils [34] . In the second region of the curve, at higher strains, the stiffness of the tendon increases [13,35] . If the strain placed on the tendon remains at less than 4%, the tendon behaves as a mechanical spring and returns to its original length and crimps when unloaded [35] .…”

“…In the second region of the curve, at higher strains, the stiffness of the tendon increases [13,35] . If the strain placed on the tendon remains at less than 4%, the tendon behaves as a mechanical spring and returns to its original length and crimps when unloaded [35] . The most probable processes are thought to be the ability of the fascicles to slide independently against each other.…”