Thermal (in)stability of type I collagen fibrils
Abstract
We measured Young's modulus at temperatures ranging from 20 to 100 C for a collagen fibril taken from rat's tendon. The hydration change under heating and the damping decrement were measured as well. At physiological temperatures 25-45C Young's modulus decreases, which can be interpreted as instability of collagen. For temperatures between 45-80C Young's modulus first stabilizes and then increases with decreasing the temperature. The hydrated water content and the damping decrement have strong maxima in the interval 70-80C indicating on complex inter-molecular structural changes in the fibril. All these effects disappear after heat-denaturating the sample at 120$C. Our main result is a five-stage mechanism by which the instability of a single collagen at physiological temperatures is compensated by the interaction between collagen molecules within the fibril.