PURIFICATION AND CHARACTERIZATION OF XYLANASE FROM ALKALI-TOLERANT ASPERGILLUS-FISCHERI FXN1

Alkali-tolerant Aspergillus fischeri Fxn1 produced two extracellular x ylanases. The major xylanase (M(r) 31 000) was purified to electrophor etic homogeneity by ammonium sulfate precipitation, anion exchange chr omatography and preparatory PAGE. Xylose was the major hydrolysis prod uct from oat spelt and birch wood xylans. It was completely free of ce llulolytic activities. The optimum pH and temperature were 6.0 and 60 degrees C, respectively. pH stability ranged from 5 to 9.5 and the t(1 /2) at 50 degrees C was 490 min. It had a K-m of 4.88 mg ml(-1) and a V-max of 588 mu mol min(-1) mg(-1). The activity was inhibited (95%) b y AlCl3 (10 mM). This enzyme appears to be novel and will be useful fo r studies on the mechanism of hydrolysis of xylan by xylanolytic enzym es.