Induction and Purification of α-L-Fucosidase from Fusarium oxysporum

Abstract

Fusarium oxysporum highly produced α-L-fucosidase inductively in the culture broth when grown in a medium containing L-fucose, which is the reaction product of the enzyme. Production of the enzyme was also slightly induced by D-arabinose, but not by other sugars including glucose. To efficiently produce the enzyme, the fungus was grown in a glucose medium at first, and then the growing mycelia were transferred to an inducing medium containing only L-fucose.
α-L-Fucosidase induced by L-fucose was purified from the inducing medium by fractionation with ammonium sulfate, DEAE-Sephadex A-50 column chromatography and gel filtration on a Sephadex G-100 column. The purified enzyme was judged to be homogeneous on polyacrylamide gel electrophoresis. The enzyme is a glycoprotein with a molecular weight of 75, 000. The enzyme can hydrolyze p-nitrophenyl α-L-fucoside, a synthetic substrate, unlike the enzymes of other microorganisms. The Km value for the substrate was 0.48 mM. The optimum pH range was 4.5-6.0 and the stable pH range 5.5-10.0. The enzyme hydrolyzed natural substrates such as porcine mucin and fucoidan to produce L-fucose.