Characterization of a recombinant sucrose isomerase and its application to enzymatic production of isomaltulose

Objective To characterize a recombinant isomerase that can catalyze the isomerization of sucrose into isomaltulose and investigate its application for the enzymatic production of isomaltulose. Results A sucrose isomerase gene fromErwinia sp. Ejp617 was synthesized and expressed inEscherichia coliBL21(DE3). The enzymatic characterization revealed that the optimal pH and temperature of the purified sucrose isomerase were 6.0 and 40 degrees C, respectively. The enzyme activity was slightly activated by Mn(2+)and Mg2+, but partially inhibited by Ca2+, Ba2+, Cu2+, Zn(2+)and EDTA. The kinetic parameters ofK(m)andV(max)for sucrose were 69.28 mM and 118.87 U/mg, respectively. The time course showed that 240.9 g/L of isomaltulose was produced from 300 g/L of sucrose, and the yield reached 80.3% after bioreaction for 180 min. Conclusions This recombinant enzyme showed excellent capability for biotransforming sucrose to isomaltulose at the substrate concentration of 300 g/L. Further investigations should be carried out focusing on selection of suitable heterologous expression system with the aim to improve its expression level.

Automated summary

The study characterized a recombinant isomerase that can convert sucrose to isomaltulose, with the enzyme showing excellent capability for this biotransformation. Further research is needed to explore suitable heterologous expression systems in order to improve its expression level.