A model for collagen hydration

Abstract

A detailed proton nuclear magnetic resonance study has been made of the influence of temperature and water content upon the nature of water adsorbed on collagen fibres. A refinement of a previously reported analysis of time-averaged tensor properties of the water molecule with respect to the fibre axis supports the previous conclusion that the water molecules form hydrogen-bonded chains around the collagen molecules. The experimental evidence strongly indicates that there is an inner hydration layer consisting of about 24 % water per weight of dry collagen, which is highly ordered, surrounded by a disordered outer layer of water at high-water contents. Exchange of water molecules between the inner and outer hydration layers takes place at a rapid rate. Dynamic aspects of the hydration structure are discussed, and it is suggested that the inner hydration layer imparts an appreciable degree of kinetic stability to the native conformation of the collagen molecule.