Collagen is the most abundant protein in the human body. It confers great stretch resistance to tissues and in particular gives elasticity to cartilage, of which it is the major component.

It is organized into multi-stranded fibers composed of three proteins wound around each other. After collagen synthesis, the solidity of the triple helix is reinforced by the addition of hydroxyl groups (OH) to proline, a very abundant amino acid in these proteins. Hence the question: is the solidity of collagen an intrinsic property of the triple helix, or is it the result of in vivo interactions with water, via the bonds with these OH groups?

A number of experiments were performed on solvent-free model molecular systems isolated from collagen. The researchers observed that the triple helix is conserved in the absence of solvent, and that its stability properties are the same as in biological tissues. The long-accepted assumption of the stabilizing effect induced by an aqueous environment must therefore be ruled out.

This work was conducted by physicists, chemists and biologists from the Centre de recherche sur les ions, les matériaux et la photonique (Cimap), in collaboration with the Institut lumière matière de Lyon and the University of Groningen (Germany). They contributed in particular to a better understanding of the consequences of cartilage irradiation in radiotherapy and hadrontherapy (especially proton therapy).