alpha-L-arabinofuranosidases from Aspergillus terreus with potential application in enology: Induction, purification, and characterization

In the presence of L-arabitol as sole carbon source, Aspergillus terreus CECT 2663 produces three alpha-L-arabinofuranosidases (ABFs) named ABF1, ABF2, and ABF3, with molecular masses of 90 000, 82 000, and 78 500 Da, respectively. The synthesis of these enzymes is under carbon catabolite repression. Western blotting revealed that ABF2 is immunologically related to the alpha-L-arabinofuranosidase B previously isolated from Aspergillus niger. The three A. terreus proteins have been purified to homogeneity. They are acidic proteins with optimal pHs of 5.0 for ABF1 and ABF2 and 5.5 for ABF3 and optimal temperatures of 50, 60, and 65 degrees C, respectively. Kinetic constants for the purified enzymes on p-nitrophenyl alpha-L-arabinofuranoside (pNPA) as substrate have been determined. The three enzymes maintain elevated activities in the presence of ethanol or glucose at those concentrations normally present in must or wine.