A β-xylosidase from cell wall of maize: Purification, properties and its use in hydrolysis of plant cell wall

To study the potential of plant glycoside hydrolase for hemicelluloses hydrolysis, a beta-xylosidase with molecular weight of 68.5 kDa was purified from the maize during senescent stage. The optimal conditions for the beta-xylosidase were 37 degrees C and pH 4.5. In absence of substrate, the beta-xylosidase was comparatively stable at 37 degrees C and pH 4.5-5.5. At the optimum condition, the K-m and k(cat) values of the beta-xylosidase against p-nitrophenyl-xyloside were 2.5 mM and 6.5 s(-1), respectively. The enzyme activity was promoted by LiCl, CaCl2, MnCl2, MgCl2, KCl. and NaCl, however severely inhibited by CuCl2, ZnCl2, AgNO3, HgCl2, and NiCl2. The purified beta-xylosidase was active against xylobiose, xylotriose, xylotetraose, and xylopentaose. In hydrolysis of corn stover hemicellulose, the xylose production increased by 94.9% and 140% when Trichoderma reesei hemicellulase supplemented with purified beta-xylosidase and crude cell wall proteins of corn stover, respectively. The biochemical characterization of the maize beta-xylosidase makes it a promising candidate enzyme additive for hemicelluloses hydrolysis. (C) 2010 Elsevier By. All rights reserved.