The effect of alkali and alkaline earth salts on the structure of hydrated collagen fibers as studied by deuterium NMR

A detailed study on the deuterium NMR of hydrated collagen in the presence of alkali and alkaline earth salt is reported. The effect of different salts in reducing the deuteron quadrupole splitting are similer at low molar content of salt. At higher salt contents, larger ions are more effective. The ressults are explained by the blocking of water binding sites to collagen by hydrated ions. When the temperature is reduced, only part of the adsorbed water iss frozen, and the amount of “unfreezable water” decreases with the increase in ionic sizes(LiCl < MgCl2 < KCL < KCNS). The freezing temperature is also lowered in the presence of salts. A description of the structure of hydrated collagen based upon the observed facts is given.