Atomic level description of the protecting effect of osmolytes against thermal denaturation of proteins

International audienceThe protecting effect of the osmolyte molecule taurine against thermal denaturation of the protein Chimotripsin Inhibitor 2 was modelled using Molecular Dynamics simulations. The protein was simulated in denaturing conditions at different taurine concentrations. Analysis of the molecular details of its behaviour shows that the protective effect of the osmolyte is concentration dependent. Moreover the influence of taurine on the solvent structure was studied. A concentration dependent ordering effect of taurine on water molecules emerges from solvent structure analysis and is well correlated to the protecting effect observed. Based on these observations an interpretation of the osmoprotective effect is proposed. Osmoprotectants are small highly soluble molecules present in all organisms. They were discovered in connection with the osmotic stress response of some living forms which can survive in extremely harsh life conditions, such as those found in desert or icy environments. Afterwards, it became evident that they can play a role as chemical chaperones, i.e. they can protect the native structure of a protein from adverse chemical and/or environmental agents which could otherwise denature the protein. Osmoprotectants have no net charge at physiological pH, and are non-toxic at high intracellula