SUBSTRATE SPECIFICITIES OF ALPHA-L-ARABINOFURANOSIDASES PRODUCED BY 2SPECIES OF ASPERGILLUS-NIGER

Precise substrate specificities of alpha-L-arabinofuranosidases from A spergillus niger 5-16 and Aspergillus niger (Megazyme) were investigat ed. Both enzymes hydrolyzed arabinan and debranched-arabinan at almost the same rate. The alpha-L-Arabinofuranosidase from A. niger (Megazym e) preferentially released arabinosyl side-chains of arabinan. The enz yme tore off both arabinoses attached to ->3)-O-beta-D-xylopyranosyl-( 1-->4)-D-xylopyranose and 3)]-O-beta-D-xylopyranosyl-(1-->4)-D-xylopyr anose, but did not tear off xylosyl-arabinose from >4)-O-beta-D-xylopy ranosyl-(1-->4)-D-xylopyranose. The enzyme from A. niger (Megazyme) hy drolyzed methyl 2-O-, methyl 3-0- and lpha-L-arabinofuranosyl-alpha-L- arabinofuranosides to arabinose and methyl alpha-L-arabinofuranoside i n the order of (1-->5)-->(1-->2)-->(1-->3)-linkages. On the other hand , alpha-L-arabinofuranosidase from A. niger 5-16 successively liberate d the arabinose of arabinan from non-reducing terminals. The enzyme hy drolyzed 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)-link age of methyl lpha-L-arabinofuranosyl-alpha-L-arabinofuranoside.