An alkali tolerant α-l-rhamnosidase from Fusarium moniliforme MTCC-2088 used in de-rhamnosylation of natural glycosides

Abstract Analkali tolerant α- l -rhamnosidase has been purified to homogeneity from the culture filtrate of a new fungal strain, Fusarium moniliforme MTCC-2088, using concentration by ultrafiltration and cation exchange chromatography on CM cellulose column. The molecular mass of the purified enzyme has been found to be 36.0 kDa using SDS-PAGE analysis. The K m value using p-nitrophenyl-α- l -rhamnopyranoside as the variable substrate in 0.2 M sodium phosphate buffer pH 10.5 at50 °C was 0.50 mM. The catalytic rate constant was15.6 s −1 giving the values of k cat /K m is 3.12 × 10 4 M −1  s −1 . The pH and temperature optima of the enzyme were 10.5 and 50 °C, respectively. The purified enzyme had better stability at 10 °C in basic pH medium. The enzyme derhamnosylated natural glycosides like naringin to prunin, rutin to isoquercitrin and hesperidin to hesperetin glucoside. The purified α - l -rhamnosidase has potential for enhancement of wine aroma.