Purification and Some Properties of a Novel α-L-Fucosidase Capable of Acting on α-(1→6)-L-Fucosidic Linkages from Bacillus circulans M28

Two types of α-L-fucosidase (F-I and F-II), that differ in substrate specificity, were produced in the culture fluid by Bacillus circulans isolated from soil when the bacterium was cultivated on medium containing porcine gastric mucin. F-I was able to cleave the α-(1→2), α-(1→3) and α-(1→4)-L-fucosidic linkages in various oligosaccharides and glyco proteins, but not p-nitrophenyl α-L-fucoside, as previously reported [Y. Tsuji et al. (1990) J. Biochem. 107, 324-330]. F-II was purified from the culture fluid obtained with glucose medium by ammonium sulfate fractionation and various subsequent column chromatogra phies. The purified enzyme was found to be homogeneous on PAGE and its molecular weight was estimated to be approximately 250,000. The maximal activity was observed between pH 6.0 to 7.0, the stable pH range being 6.0 to 8.5. The enzyme specifically cleaved a L-fucosidic bonds in low molecular weight substrates. The enzyme cleaved not only p-nitrophenyl α-L-fucOSide, but also 2′-fucosyllactose and 3-fucosyllactose. The enzyme was also able to act on the α-(1→6)-L-fucosidase linkages to N-acetyiglucosamine in 6-O-α L-fucopyranosyl-N-acetylglucosamlne, and bi- and tetrα-antennary oligosaceharides derived from porcine pancreatic lipase, which were not hydrolyzed by F-I.