alpha-L-RHAMNOSIDASE FROM Aspergillus clavato-nanicus MTCC-9611 ACTIVE AT ALKALINE pH

摘要

An alpha-L-rhamnosidase secreting fungal strain has been isolated and identified as Aspergillus clavato-nanicus MTCC-9611. The enzyme was purified to homogeneity from the culture filtrate of the fungus using concentration by ultrafiltration membrane and ion-exchange chromatography on CM-cellulose. The native PAGE analysis confirmed the homogeneity of the purified enzyme. The SDS-PAGE analysis of the purified enzyme revealed a single protein band corresponding to the molecular weight 82 к Da. The a-L-rhamnosidase activity of Aspergillus clavato-nanicus MTCC-9611 had optimum at рН 10.0 and 50°C. The K_m values of the enzyme were 0.65 mM and 0.95 mM using p-nitrophenyl a-L-rhamnopyranoside and naringin as a substrates respectively. The enzyme transforms naringin to prunin at pH 10.0 and further hydrolysis of prunin to naringenin does not occur under these reaction conditions that makes a-L-rhamnosidase activity of Aspergillus clavato-nanicus MTCC-9611 promising enzyme to get pmnin for pharmaceutical purposes.