Abstract
Precise substrate specificities of α-L-arabinofuranosidases from Aspergillus niger 5-16 and Aspergillus niger (Megazyme) were investigated. Both enzymes hydrolyzed arabinan and debranched-arabinan at almost the same rate. The α-L-Arabinofuranosidase from A. niger (Megazyme) preferentially released arabinosyl side-chains of arabinan. The enzyme tore off both arabinoses attached to O-α-L-arabinofuranosyl-(1→3)-O-β-D-xylopyranosyl-(1→4)-D-xylopyranose and O-β-D-xylopyranosyl-(1→4)-[O-α-L-arabinofuranosyl-(1→3)]-O-β-D-xylopyranosyl-(1→4)-D-xylopyranose, but did not tear off xylosyl-arabinose from O-β-D-xylopyranosyl-(1→2)-O-α-L-arabinofuranosyl-(1→3)-O-β-D-xylopyranosyl-(1→4)-O-β-D-xylopyranosyl-(1→4)-D-xylopyranose. The enzyme from A. niger (Megazyme) hydrolyzed methyl 2-O-, methyl 3-O- and methyl 5-O-α-L-arabinofuranosyl-α-L-arabinofuranosides to arabinose and methyl α-L-arabinofuranoside in the order of (1→5)->(1→2)->(1→3)-linkages. On the other hand, α-L-arabinofuranosidase from A. niger 5-16 successively liberated the arabinose of arabinan from non-reducing terminals. The enzyme hydrolyzed in the order of (1→2)->(1→3)->(1→5)-linkages. Both of the enzymes hydrolyzed the (1→3)-linkage more than the (1→5)-linkage of methyl 3,5-di-O-α-L-arabinofuranosyl-α-L-arabinofuranoside.
