Purification and Characterization of Two Endo-1,4-β-Xylanases from Aspergillus Awamori K-1

ABSTRACT

Two xylanases (1,4-β-D-xylan xylanohydrolase; EC 3.2.1.8) were isolated from the culture broth of Aspergillus awamori K-1. The enzymes were purified 9.81 and 18. 71-fold by ammonium sulfate precipitation, ultrafiltration, gel and anion-exchange chromatographic methods. The homogeneity of the purified endo-1,4-β-xylanases was assessed by SDS/PAGE and molecular-sieve chromatography on Superose 12 column. The enzymes have relative molecular masses (Mr) of 23 kDa and 27 kDa as detected by SDS/PAGE and isoelectric points (pI_s of 3.45 and 3.75, respectively. The optimum pH and temperature values were 4.7 and 45 °C for xylanase II (Xyl II) and 3.0 and 50 °C for xylanase III (Xyl III). The products of the enzymatic hydrolysis of different xylans were analyzed by HPLC. The hydrolysis pattern showed that the xylanases purified in the present study were endo-acting enzymes. The K_m and V values with three xylans as substrates were determined.