The disaccharide trehalose is generally acknowledged
as a superior
stabilizer of proteins and other biomolecules in aqueous environments.
Despite many theories aiming to explain this, the stabilization mechanism
is still far from being fully understood. This study compares the
stabilizing properties of trehalose with those of the structurally
similar disaccharide sucrose. The stability has been evaluated for
the two proteins, lysozyme and myoglobin, at both low and high temperatures
by determining the glass transition temperature, T
g, and the denaturation temperature, T
den. The results show that the sucrose-containing samples
exhibit higher T
den than the corresponding
trehalose-containing samples, particularly at low water contents.
The better stabilizing effect of sucrose at high temperatures may
be explained by the fact that sucrose, to a greater extent, binds
directly to the protein surface compared to trehalose. Both sugars
show T
den elevation with an increasing
sugar-to-protein ratio, which allows for a more complete sugar shell
around the protein molecules. Finally, no synergistic effects were
found by combining trehalose and sucrose. Conclusively, the exact
mechanism of protein stabilization may vary with the temperature,
as influenced by temperature-dependent interactions between the protein,
sugar, and water. This variability can make trehalose to a superior
stabilizer under some conditions and sucrose under others.