Patent ID: 7491518

Claim:
A method of producing an oligosaccharide containing an α-galactosyl group comprising the steps of treating galactose or a galactose-containing material with an α-galactosidase derived from Aspergillus niger strain APC-9319 (FERM BP-7680), wherein: a) said α-galactosidase catalyzes the hydrolysis of an α-galactoside bond to liberate D-galactose and the reverse reaction of dehydrocondensation of a free galactose and a compound containing a hydroxyl group to a saccharide containing an α-galactosyl group: Gal1α-OR+H20⇄Gal-OH+R—OH wherein Gal1α-OR is a saccharide containing an α-galactosyl group, Gal-OH is a free galactose, and R—OH is a compound containing a hydroxyl group; b) said α-galactosidase acts on a saccharide having an α-galactosyl group at the non-reducing terminal end of said saccharide; c) said α-galactosidase has a pH optimum of 2.5 to 6.0; and said α-galactosidase is stable within the range pH 3.5 to 8.0 when allowed to stand for one hour at 40° C.; d) said α-galactosidase has an optimum temperature of 60° C. at pH 4.5; and said α-galactosidase is stable at a temperature of not greater than 60° C. when allowed to stand at pH 4.5 for 15 minutes; e) said α-galactosidase has a molecular weight of 217,000 Daltons measured by gel filtration; and said α-galactosidase has a molecular weight of 117,000 Daltons measured by an SDS-PAGE; and f) said α-galactosidase has an isoelectric point of 4.2 measured by isoelectric focusing; and recovering the oligosaccharide containing the α-galactosyl group.