Characterization of a novel xylose isomerase from Anoxybacillus gonensis G2(T)

The xylA gene encoding xylose isomerase from Anoxybacillus gonensis G2(T) has been cloned and successfully expressed in E. coli. Xylose isomerase was purified 10.98-fold by heat-shock and sequential column chromatography techniques to homogeneity, and the biochemical properties of the enzyme were characterized. The optimum temperature of the enzyme was 85 degrees C and maximum activity was observed at a pH of 6.5. Its Km and Vmax values were calculated as 25 +/- 2 mM and 0.12958 +/- 0.002 mu mol/min/mg protein, respectively. The effects of various metal ions on the xylose isomerase were examined. Divalent cations Co2+, Mg2+, and Mn2+ were essential for xylose isomerase activity; however, bivalent metal ions (Ca2+, Hg2+, Ni2+, Zn2+, Fe2+, and Cu2+) showed inhibitory effects. This is the first report of characterization of the xylose isomerase of Anoxybacillus spp. According to results obtained from this study, xylose isomerase is a promising candidate for industrial applications in production of xylulose and ribose.