Abstract
BackgroundType I collagen is the most common protein among higher vertebrates. It forms the basis of fibrous connective tissues (tendon, chord, skin, bones) and ensures mechanical stability and strength of these tissues. It is known, however, that separate triple-helical collagen macromolecules are unstable at physiological temperatures. We want to understand the mechanism of collagen stability at the intermolecular level. To this end, we study the collagen fibril, an intermediate level in the collagen hierarchy between triple-helical macromolecule and tendon.Methodology/Principal FindingWhen heating a native fibril sample, its Young’s modulus decreases in temperature range 20–58°C due to partial denaturation of triple-helices, but it is approximately constant at 58–75°C, because of stabilization by inter-molecular interactions. The stabilization temperature range 58–75°C has two further important features: here the fibril absorbs water under heating and the internal friction displays a peak. We relate these experimental findings to restructuring of collagen triple-helices in fibril. A theoretical description of the experimental results is provided via a generalization of the standard Zimm-Bragg model for the helix-coil transition. It takes into account intermolecular interactions of collagen triple-helices in fibril and describes water adsorption via the Langmuir mechanism.Conclusion/SignificanceWe uncovered an inter-molecular mechanism that stabilizes the fibril made of unstable collagen macromolecules. This mechanism can be relevant for explaining stability of collagen.
Highlights
Type I collagen is the most common protein among higher vertebrates
Theoretical Results and Discussion The purpose of the following theoretical consideration is to come up with the simplest equilibrium model of the fibril, which under natural assumptions of polymer physics will model the dominance of intermolecular interactions under increasing the temperature, and as a result of this dominance will lead to non-monotonous water adsorption
In this paper we studied the Young’s modulus, the hydrated water content and the logarithmic decrement of damping for collagen fibrils
Summary
Type I collagen is the most common protein among higher vertebrates It forms the basis of fibrous connective tissues, such as tendon, chord, skin, bones, cornea and dentine [1,2]. It forms the basis of fibrous connective tissues (tendon, chord, skin, bones) and ensures mechanical stability and strength of these tissues. It is known, that separate triple-helical collagen macromolecules are unstable at physiological temperatures. We study the collagen fibril, an intermediate level in the collagen hierarchy between triple-helical macromolecule and tendon
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