Abstract
A β-glucosidase from Penicillium italicum was purified with a specific activity of 61.8 U/mg, using a chromatography system. The native form of the enzyme was an 88.5-kDa tetramer with a molecular mass of 354 kDa. Optimum activity was observed at pH 4.5 and 60°C, and the half-lives were 1,737, 330, 34, and 1 hr at 50, 55, 60, and 65°C, respectively. Its activity was inhibited by 47% by 5 mM Ni2+. The enzyme exhibited hydrolytic activity for p-nitrophenyl-β-D-glucopyranoside (pNP-Glu), p-nitrophenyl-β-D-cellobioside, p-nitrophenyl-β-D-xyloside, and cellobiose, however, no activity was observed for p-nitrophenyl-β-D-lactopyranoside, p-nitrophenyl-β-D-galactopyranoside, carboxymetyl cellulose, xylan, and cellulose, indicating that the enzyme was a β-glucosidase. The kcat/Km (s-1 mM-1) values for pNP-Glu and cellobiose were 15,770.4 mM and 6,361.4 mM, respectively. These values were the highest reported for β-glucosidases. Non-competitive inhibition of the enzyme by both glucose (Ki = 8.9 mM) and glucono-δ-lactone (Ki = 11.3 mM) was observed when pNP-Glu was used as the substrate. This is the first report of non-competitive inhibition of β-glucosidase by glucose and glucono-δ-lactone.
Original language | English |
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Pages (from-to) | 173-180 |
Number of pages | 8 |
Journal | Mycobiology |
Volume | 40 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2012 |
Keywords
- Cellulolytic fungi
- Characterization
- Identification
- Purification
- β-Glucosidase
ASJC Scopus subject areas
- Microbiology
- Infectious Diseases