Purification and Characterization of β-Glucosidase from Penicillium janthinellum Mutant EU2D-21

Background: β-Glucosidases are terminal enzymes in cellulose hydrlysis which hydrolyze glycosidic bonds between two or more carbohydrates. Not much information is available on purification and characterization of β-glucosidase from Penicillium janthinellum. Here we report the purification and characterization of thermostable β-glucosidase from P. janthinellum mutant EU2D-21 produced under submerged conditions. Methods: The thermostable β-glucosidase was purified to homogeneity by anion exchange chromatography followed by gel permeation chromatography. It was characterized for its physical and biochemical properties using variety of methods such as MALDI-TOF MS, SDS-PAGE, CD spectra, pH and temperature optima and stability. Results: The protocol followed for purification resulted in high recovery of purified enzyme with specific activity increased from 1.0 to 169.84 IU/mg. It is a glycoprotein with molecular mass of 120 kDa as estimated by SDS-Page and MALDI-TOF MS. The enzyme is active at pH 4.5 and temperature 65°C. The purified β-glucosidase possesses tryptophan and carboxyl residues and histidine at the active site. Tandem MS analysis and MASCOT based database interrogations revealed low homology with known beta-glucosidases including of P. decumbens. The absence of a protein match with any P. janthinellum entries indicate that this β-glucosidase sequence has not been previously reported. Conclusions: The study demonstrated the importance of this enzyme at commercial levels for the hydrolysis of lignocellulose to their monomers. Tandem MS analysis and MASCOT based database interrogations revealed low homology with known beta-glucosidases including of P. decumbens. The absence of a protein match with any P. janthinellum entries indicate that this β-glucosidase sequence has not been previously reported.