ALPHA-L-ARABINOFURANOSIDASE PRODUCTION BY ASPERGILLUS-NIDULANS

The effects of some physico-chemical parameters on production of extra cellular alpha-L-arabinofuranosidase by Aspergillus nidulans were exam ined. Highest levels of alpha-L-arabinofuranosidase were generated wit h cultures grown on 1% (w/v) purified beet pulp arabinan at 30 degrees C and at an initial pH of 7.0. The enzyme was shown to be very sensit ive to the action of proteases. Zymogram overlay of a protein profile obtained by SDS-PAGE revealed the occurrence of a band (M(r) 36000) ex hibiting alpha-L-arabinofuranosidase activity. The isoelectric pH of t he enzyme lay near 4.3. Temperature and pH optima for the activity of crude alpha-L-arabinofuranosidase preparations were 55 degrees C and 5 .5, respectively. Enzyme activity was greatly reduced by thiol reagent s such as Hg2+ and p-hydroxymercuribenzoate and showed a K-m value of 2.7 mM on p-nitrophenyl alpha-L-arabinofuranoside as substrate.