Construction of the trifunctional enzyme associating the Thermoanaerobacter ethanolicus xylosidase-arabinosidase with the Thermomyces lanuginosus xylanase for degradation of arabinoxylan

The trifunctional enzyme (XAR–XYN) associating the Thermoanaerobacter ethanolicus xylosidase-arabinosidase (XAR) with the Thermomyces lanuginosus xylanase (XYN) was produced in E. coli to study the effect of the physical association of the fusion partners on the enzymatic efficiency. Recombinant XAR, XYN and XAR–XYN were purified to homogeneity and characterized. The optimal pH and temperature of the XAR–XYN were found to be similar to those of the XAR and XYN, except for less temperature optimum of α-arabinosidase activity. Its pH and xylanase activity exhibited more stable than those of the XAR and XYN. Finally, the XAR–XYN was tested for degradation of oat spelt xylan and wheat bran, the XAR–XYN was found to be more facile than the corresponding free enzyme degradation of wheat bran but provided little or no advantage on purified xylan. Furthermore cooperation within a trifunctional enzyme containing linker SAGSSAAGSGSG between each partner was achieved, leading to a trifunctional enzyme with enhanced enzymatic efficiency on arabinoxylan.