PURIFICATION AND SOME PROPERTIES OF INTRACELLULAR ALPHA-L-ARABINOFURANOSIDASE FROM ASPERGILLUS-NIGER 5-16

Alpha-L-arabinofuranosidase was purified from a cell-free extract of A spergillus niger 5-16 by chromatographies on DEAE-Toyopearl, SP-Toyope arl, Ultro-gel AcA 44, Mono P, and TSK-Gel G3000SW. The final preparat ion thus obtained showed a single band on SDS-polyacrylamide gel elect rophoresis. The molecular weight and isoelectric point were 67,000 by SDS-polyacrylamide gel electrophoresis and pH 3.5 by isoelectric focus ing. The alpha-L-arabinofuranosidase contained amino acids in the orde r of Asx > Gly > Ala > Thr > Glx = Ser. The enzyme had maximum activit y at pH 4.0 and 60-degrees-C, and was stable from pH 4 to 7 and at tem peratures up to 30-degrees-C. The enzyme activity was not affected con siderably by either metal ions or chemical reagents. The enzyme releas ed arabinose from p-nitrophenyl-alpha-L-arabinofuranoside, >3)-O-beta- D-xylopyranosyl-(1-->4)-D-xylopyranose, and arabinan, but not from L-a rabinofuranosyl-(1-->3)!-O-beta-D-xylopyranosyl (1-->4)-D-xylopyranose , -L-arabinofuranosyl-(1-->3)-O-beta-D-xylopyranosyl >4)-O-beta-D-xylo pyranosyl-(1-->4)-D-xylopyranose, gum arabic, or arabinoxylan. The lim it of hydrolysis of arabinan was about 58% even when the enzyme was su fficiently in excess.