Nuclear Magnetic Resonance Study of Collagen Hydration

The proton resonance signal of water in partially dried tendon shows three peaks for samples equilibrated in an atmosphere of 30%—80% relative humidity (R.H.). The outer-peak splitting (between 0.5 and 1 gauss) has the character of a proton-pair splitting with effective interactions in, or close to, the fiber direction, as concluded from the dependence of the absorption on the angle between the fiber direction and the magnetic field. Chainlike water structures, exhibiting certain proton-reorientation processes, are postulated. At 10% R.H. a narrow peak is observed, which is not angular dependent; this indicates rapid reorientation of water molecules. Above 80%—90% R.H., a single peak is observed, the width of which has a strong angular dependence. A structural relationship between collagen and water exists, by virtue of which the existence of water chains and, possibly, of three-dimensional water structures, could be stabilized.