Purification and characterization of extracellular 1,2-α-L-fucosidase from Bacillus cereus

Bacillus cereus isolated from a soil sample, inductively produced α-L-fucosidase in culture medium containing porcine gastric mucin (PGM). The production of the enzyme was also weakly induced by L-fucose and D-arabinose, but not by other sugars including glucose. The enzyme was purified 61-fold with an overall recovery of 1.8% from the culture fluid supplemented with PGM by ammonium sulfate precipitation, acetone fractionation, and subsequent column chromatography. The purified enzyme was found homogeneous by SDS-PAGE and its molecular mass was estimated to be approximately 196,000 kDa. Its optimum pH was 7.0 and it was stable in the pH range of 5.0 to 9.0. The enzyme hydrolyzed the α-(1→2)-L-fucosidic linkage in oligosaccharides such as Fucα1-2Galβ1-4Glc (2′-fucosyllactose), Fucα1-2Galβ1-3GlcNAcβ1-3Galβ1-4Glc (lacto-N-fucopentaose I), and the glycoprotein PGM. The enzyme was inactive on p-nitrophenyl α-L-fucoside, the α-(1→3)-L-fucosidic linkages in Galβ1-4(Fucα1-3)GlcNAcβ1-3Galβ1-4Glc (lacto-N-fucopentaose III) and orosomucoid, the α-(1→4)-L-fucosidic linkage in Galβ1-3(Fucα1-4)GlcNAcβ1-3Galβ1-4Glc (lacto-N-fucopentaose II), and the α-(1→6)-L-fucosidic linkage in thyroglobulin.