Characterization and Functional Expression of Xylose Isomerase from Thermus thermophilus

Ethanol produced from hexose and pentose sugars hydrolysated by lignocellulose is an environment-friendly alternative to fossil fuels. Xylose isomerase is the major rate-limiting enzyme in the ethanol synthesis biologically pathway of xylose fermentation. In present study, xylA gene encoding xylose isomerase was cloned from Thermus thermophilus and overexpressed in E. coli BL21. Purified recombinant enzyme was used to study the enzymatic characterization. Specific activity of recombinant PDOR was 19.6 U/mg. Optimal temperature and pH were 80 °C, 8.0, respectively. Km and Vmax values were 15.9 mM, 22.8 U/mg. This research may form a basis for the future application of xylose isomerase.