Purification and characterization of xylanase from Aspergillus ficuum AF-98

The purification and characterization of xylanase from Aspergillus ficuum AF-98 were investigated in this work. The extracellular xylanase from this fungal was purified 32.6-fold to homogeneity throughout the precipitation with 50-80% (NH4)(2)SO4, DEAE-Sephadex A-50 ion exchange chromatography and Sephadex G-100 chromatography. The purified xylanase (specific activity at 288.7 U/mg protein) was a monomeric protein with a molecular mass of 35.0 kDa as determined by SDS-PAGE. The optimal temperature and pH for the action of the enzyme were at 45 degrees C and 5.0, respectively. The xylanase was activated by Cu2+ up to 115.8% of activity, and was strongly inhibited by Hg2+, Pb2+ up to 52.80 o and 89%, respectively. The xylanase exhibited Km and Vn,,x values of 3.267 mg/mL, 18.38 M/min/mg for beechwood xylan and 3.747 mg/mL, 11.1 M/min/mg for birchwood xylan, respectively. (C) 2007 Elsevier Ltd. All rights reserved.