Purification and characterization of three alfa-arabinosidases from Aspergillus terreus

Three α-arabinosidases were purified from a culture filtrate of Aspergillus terreus VTT-D-82209 grown on sugar beet extraction waste as carbon source. The isoelectric points were 7.5, 8.3 and 8.5, and the molecular masses as determined by SDS-PAGE were 39, 59 and 59 kDa, respectively. The optimum pH was 3.5–4.5 for all three α-arabinosidases. The pI 8.5 enzyme was more stable at higher pH and temperature than the other two. All three α-arabinosidases were able to hydrolyze p-nitrophenyl-a-L-arabinofuranoside, oat spelt arabinoglucuronoxylan, rye flour arabinoxylan and rye flour. About 80% of the total arabinose of arabinoglucuronoxylan isolated from softwood kraft pulp was hydrolyzed with all three enzymes, but the hydrolysis yield of arabinose from arabinoglucuronoxylan isolated from bleached pulp was low.
The amount of arabinose released did not significantly increase in simultaneous hydrolysis with xylanase.