Thermodynamic characterization of the betaine and sarcosin effect on Protein stability

Osmolytes are cosolvents that are used to protect organism from harsh environmental stresses. These molecules stabilize proteins, not interacting with them directly but altering the solvent properties of surrounding water and hence protein-solvent interactions [۱].their effect seems to be general for all proteins. Those having enhancing effect on protein functions are called counteracting osmolytes and those having no inhibitory or enhancing effect are called compatible osmolytes [۲]. There are various mechanisms that have been used to explain the observation on the effect of osmolytes on the protein denaturation equilibrium, native (N) state denatured (D) satte [۳]. The most widely used mechanism is due to Timasheff. Small proteins tend to exhibit all-or-none transitions between their native and unfolded forms in equilibrium. This holds particularly for equilibrium conditions, while in kinetic measurements there may be folding intermediates, or temporary off-pathway misfolding events. Such all-or-none transitions are characterized by a shift in population, where fully native proteins are in equilibrium with fully denatured proteins. The stability of a protein is defined as the difference in Gibbs free energy between the denatured (D) and native (N) state: (...)

کلیدواژه ها:

Denaturation ، Osmolytes ، Betaine ، Sarcosin ، Protein stability