Purification and characterization of α-l-rhamnosidase from Penicillium corylopholum MTCC-2011

• Secretion of α-l-rhamnosidase by a new fungal strain Penicillium corylopholum MTCC-2011 shown.
• Corn cob is an inducer for P. corylopholum α-l-rhamnosidase.
• α-l-Rhamnosidase of P. corylopholum has been purified to homogeneity.
• The enzyme is suitable for the preparation of l-rhamnose, prunin and quercetin glucoside.

An extracellular α-l-rhamnosidase has been purified to electrophoretic homogeneity from the culture filtrate of Penicillium corylopholum MTCC-2011 using a simple procedure consisting of concentration by ultrafiltration and cation exchange column chromatography on carboxymethyl cellulose. The sodium dodesyl sulphate polyacrylamide gel electrophoresis analysis of the purified enzyme gave a single protein band corresponding to the molecular mass of 67.0 kDa. The native – polyacrylamide gel electrophoresis analysis also gave a single protein band confirming the purity of the enzyme and also showing that the enzyme is a monomer in the native state. The Km and kcat values of the enzyme were 0.42 mM and 35.7 s−1, respectively, using p-nitrophenyl α-l-rhamnopyranoside as the substrate. The pH and temperature optima of the enzyme were 6.5 and 57.0 °C, respectively. The purified enzyme preparation successfully hydrolyzed naringin and rutin to prunin and quercetin glucoside, respectively. Thus it can be used for the preparation of these pharmaceutically important compounds.