Abstract:The thermal stability of enzyme is an important target of industrial enzyme property modification. As an exogenous additive widely used to improve enzyme stability, the mechanism of sorbitol affecting enzyme thermal stability is still unclear. Therefore, the authors focused onα-L-rhamnosidase (r-Rha1) derived from Aspergillus niger and investigated the mechanism of sorbitol on the thermal stability of α-L-rhamnosidase by thermal inactivation kinetics, circular dichroism and spectroscopic analysis of fluorescence mapping. Adding sorbitol improved the thermal stability of α-L-rhamnosidase at 60~70 ℃， and 1.2 mol/L sorbitol increased the half-life of α-L-rhamnosidase 29-fold, 25-fold and 10-fold at 60, 65 ℃ and 70 ℃, respectively. The results of circular dichroism and fluorescence mapping plus indicated that sorbitol improved the thermal stability of α-L-rhamnosidase by enhancing its surface hydrophobic activity and structural rigidity. The effect of sorbitol on the thermal stability of α-L-rhamnosidase was investigated to further prove the general applicability of sorbitol in improving the thermal stability of the enzyme, while providing a reference for the subsequent industrial application of α-L-rhamnosidase.
