Rational design of xylose dehydrogenase for improved thermostability and its application in development of efficient enzymatic biofuel cell.

In this paper, the construction of 3D model structure of xylose dehydrogenase (XDH) by using homology modeling to guide the rational design of the enzyme for improving thermostability was reported. Three XDH mutants of NA-1 (+249L), NA-2 (G149P) and NA-3 (+249L/G149P) were designed and displayed on the surface of bacteria. Among them, bacteria displaying NA-1 (NA-1-bacteria) exhibited superior thermostability without compromising its activity and substrate specificity in comparison with its wild-type counterpart. NA-1-bacteria retained its original activity after incubation at room temperature for one-month with the half-life of 9.8 days at 40°C. Finally, the NA-1-bacteria were applied to construct xylose/O2 based biofuel cell with good performance including enhanced operational stability. Thus, the approach described here could be explored for engineering of other enzymes for improving certain characters without three-dimensional structure identified by experimental methods.