| Abstract: | The coil-to-helix transition temperatures of hydrogen bearing and deuterated poly(γ-benzyl-L -glutamate) in 1,3-dichlorotetrafluoroacetone/H2O and/D2O mixtures, respectively, have been determined. Together with previously obtained data for the conformational transition of this polypeptide in normal and deuterated dichloroacetic acid, these results have been used in an analysis of the effect of deuterium substitution on the intrinsic stability of the α-helical form of poly(γ-benzyl-L -glutamate). The findings, consistent for both solvent systems, showed that the deuterated polypeptide is some 5% more stable than the normal protonated poly(γ-benzyl-L -glutamate), while the polypeptide-active solvent interaction enthalpy is also slightly increased by deuterium substitution in the respective molecules. A consideration of available data for poly(β-benzyl-L -aspartate) reveals an anomaly with respect to the present analysis. |
