Effect of dioxane molecules on the hydration shell of polypeptides

Our interest in the modifying influence of low-molecular-weight organic compounds on the hydration shell of biopolymers is due to a well-known fact that the former can act as regulators of the enzymatic activity changing the hydration shell of the latter. Dioxane was chosen because of its wide application in non-aqueous biocatalysis. In the present study, we investigate the mechanisms of dioxane influence on water of the first hydration layer of the model polypeptides by FTIR-spectroscopy during simultaneous sorption of water-dioxane vapors into the polypeptide films at low water activity. It was found that modification of the hydration shell of the polypeptides studied was mainly due to the indirect ordering of polypeptide secondary structure with the penetration of dioxane molecules under these conditions.