|
Why Is Trehalose an Exceptional Protein Stabilizer? |
|
|
|
AN ANALYSIS OF THE THERMAL STABILITY OF PROTEINS IN THE PRESENCE OF THE COMPATIBLE OSMOLYTE TREHALOSE Jai K. Kaushik and Rajiv Bhat
From the Centre for Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India Journal Biol. Chem., Vol. 278, Issue 29, 26458-26465, July 18, 2003 Trehalose, a naturally occurring osmolyte, is known to be an exceptional stabilizer of proteins and helps retain the activity of enzymes in solution as well as in the freeze-dried state. To understand the mechanism of action of trehalose in detail, we have conducted a thorough investigation of its effect on the thermal stability in aqueous solutions of five well characterized proteins differing in their various physico-chemical properties.
Among them, RNase A has been used as a model enzyme to investigate the effect of trehalose on the retention of enzymatic activity upon incubation at high temperatures. 2 M trehalose was observed to raise the transition temperature, Tm of RNase A by as much as 18 °C and Gibbs free energy by 4.8 kcal mol–1 at pH 2.5. There is a decrease in the heat capacity of protein denaturation Cp) in trehalose solutions for all the studied proteins. An increase in the G and a decrease in the Cp values for all the proteins points toward a general mechanism of stabilization due to the elevation and broadening of the stability curve G versus T). A direct correlation of the surface tension of trehalose solutions and the thermal stability of various proteins has been observed. Wyman linkage analysis indicates that at 1.5 M concentration 4–7 molecules of trehalose are excluded from the vicinity of protein molecules upon denaturation. We further show that an increase in the stability of proteins in the presence of trehalose depends upon the length of the polypeptide chain. The pH dependence data suggest that even though the charge status of a protein contributes significantly, trehalose can be expected to work as a universal stabilizer of protein conformation due to its exceptional effect on the structure and properties of solvent water compared with other sugars and polyols.Sugar Science Forum Editor’s note: Osmolytes are organic compounds affecting osmosis and soluble in the solution within a cell. Osmolytes play a role in maintaining cell volume and fluid balance. As external osmotic pressure is placed on the cell, the membrane channels open and allow efflux of osmolytes carrying water with them to restore normal cell volume. |
|
Last Updated ( Jul 21, 2008 at 09:23 AM )
|
