Increased Thermal Stability of Collagen in the Presence of Sugars and Polyols1

The effects of sugars and polyols on the thermal denaturation temperature, Tm, of acid-soluble collagen from calf skin were studied at pH 4.0 under atmospheric pressure as well as high pressures up to 4,000 atm. Addition of these compounds invariably raised Tm with increases in their concentration over the whole range of pressure. The extent of stabilization by different sugars and polyols is discussed in terms of their different influences on the structure of water. The hydroxymethyl chain length of polyols and equatorial OH groups of the sugars were found to be decisive factors for their stabilizing effect on collagen structure. The similarity in their stabilizing effects on collagen and globular proteins suggests that our stabilization mechanism proposed for globular proteins can be essentially extended to fibrous proteins: such protein stabilization would be dominantly mediated through a preferential hydration of protein, originating in the water-structure-making character of sugars and polyols.