Effects of H2O and D2O on polyproline II helical structure.

The interaction of solvent with a polypeptide chain is one of the primary factors controlling protein folding and stability. In biologically relevant systems, this solvent is most often water. Experimental estimates of the role of water in peptide folding can be obtained from solvent perturbation experiments. The simplest perturbant for H2O water is its isotopic D2O form. The solvation of peptides known to form PII helices with D2O versus H2O increases their propensity to adopt the PII conformation.