Mechanism of Osmolyte Stabilization-Destabilization of Proteins: Experimental Evidence.

In this work, we investigated the influence of stabilizing (,,-trimethylglycine) and destabilizing (urea) osmolytes on the hydration spheres of biomacromolecules in folded forms (-1 peptide and hen egg white lysozyme─) and unfolded protein models (glycine─GLY and -methylglycine─NMG) by means of infrared spectroscopy. GLY and NMG were clearly limited as minimal models for unfolded proteins and should be treated with caution. We isolated the spectral share of water changed simultaneously by the biomacromolecule/model molecule and the osmolyte, which allowed us to provide unambiguous experimental arguments for the mechanism of stabilization/destabilization of proteins by osmolytes.