FIG. 3.

xyl3A encodes a functional β-xylosidase. (A) Purification of recombinant Xyl3A. The eluate from cobalt chelate chromatography was analyzed by 12% SDS-PAGE, followed by Coomassie brilliant blue G-250 staining. MW, molecular weight (in thousands). (B) Gel filtration chromatography. The size of purified Xyl3A was estimated by size exclusion chromatography. The molecular weight (MW, in thousands; reported as the mean ± standard deviation from three independent experiments) of Xyl3A was calculated from the retention time of the peak absorbance by comparison with calibration standards having known molecular weights. mAU, milli-absorbance units. (C) Hydrolysis of pNP-linked sugars. Xyl3A was assessed for its capacity to hydrolyze several pNP-linked sugars by UV spectroscopy. Values are means ± standard deviations from three independent experiments. (D) Hydrolysis of xylo-oligosaccharides. Xyl3A-catalyzed hydrolysis of xylo-oligosaccharides (X₂ to X₆) was assessed by incubating the enzyme with each substrate and then resolving the products by TLC followed by staining with methanolic orcinol.