Gelatin gels in deuterium oxide

Gelatin gels formed in D2O have greater rigidity than gels of equal concentration formed in H2O. In D2O the junction zones (regions of collagen triple helix structure) were smaller (i.e. involved fewer amino acid residues) than in H2O. The contribution per amino acid residue to the free energy of formation of junction zones was −0.51 kJ/mol in D2O compared with −0.34 kJ/mol in H2O, consistent with the fact that hydrogen bonds are stronger in D2O than in H2O. Gels formed in D2O also have higher melting temperatures (Tm) than corresponding gels formed in H2O. This increase in Tm accounted for the faster rate of gelation in D2O compared with H2O.