Purification and characterization of a low molecular weight xylanase from solid-state cultures of Aspergillus fumigatus fresenius

A xylan-degrading enzyme (xylanase II) was purified to apparent homogeneity from solid-state cultures of Aspergillus fumigatus Fresenius. The molecula r weight of xylanase LI was found to be 19 and 8.5 kDa, as estimated by SDS -PAGE and gel filtration on FPLC, respectively. The purified enzyme was mos t active at 55 degrees C and pH 5.5. It was specific to xylan. The apparent K-m and V-max values on soluble and insoluble xylans from oat spelt and bi rchwood showed that xylanase II was most active on soluble birchwood xylan. Studies on hydrolysis products of various xylans and xylooligomers by xyla nase II on HPLC showed that the enzyme released a range of products from xy lobiose to xylohexaose, with a small amount of xylose from xylooligomers, a nd presented transferase activity.