Exchange of the structural water of collagen and alcanol-induced molecular rearrangement

The exchange of the structural water of collagen for alcanols was investigated using X-ray diffraction combined with mechanical measurements. The stepwise dehydration with methanol, ethanol or 1-propanol is reflected by the reversible loss of the characteristic equatorial reflexions of native rat tail tendons. The stepwise dehydration with 2-propanol leads first to a loss of the equatorial reflexions that are characteristic of native collagen, then to their reappearance at smaller diffraction angles. Stereochemical requirements are discussed as well as consequences for the structural model of collagen.