Biochemical and catalytic properties of two intracellular β-glucosidases from the fungus Penicillium decumbens active on flavonoid glucosides

• Published in: Journal of molecular catalysis. B, Enzymatic Enzymatic, 2004, Vol.27 (4), p.183-190
• Main Authors: Mamma, Diomi, Hatzinikolaou, Dimitris G, Christakopoulos, Paul
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Deglycosylation; Flavonoids glycosides; Fundamental and applied biological sciences. Psychology; Kinetics; Miscellaneous; Mission oriented research; Penicillium decumbens; Purification; β-Glucosidases
• ISSN: 1381-1177; 1873-3158; 1873-3158
• DOI: 10.1016/j.molcatb.2003.11.011

In the presence of rutin as sole carbon source, Penicillium decumbens produces two intracellular β-glucosidases named G I and G II, with molecular masses of 56,000 and 460,000 Da, respectively. The two proteins have been purified to homogeneity. G I and G II composed of two and four equal sub-units, respectively and displayed optimal activity at pH 7.0 and temperature 65–75 °C. Both β-glucosidases were competitively inhibited by glucose and glucono-δ-lactone. G I and G II exhibited broad substrate specificity, since they hydrolyzed a range of (1,3)-, (1,4)- and (1,6)-β-glucosides as well as aryl β-glucosides. Determination of k cat/ K m revealed that G II hydrolyzed 3–8 times more efficiently the above-mentioned substrates. The ability of G I and G II to deglycosylate various flavonoid glycosides was also investigated. Both enzymes were active against flavonoids glycosylated at the 7 position but G II hydrolyzed them 5 times more efficiently than G I. Of the flavanols tested, both enzymes were incapable of hydrolyzing quercetrin and kaempferol-3-glucoside. The main difference between G I and G II as far as the hydrolysis of flavanols is concerned, was the ability of G II to hydrolyze the quercetin-3-glucoside.