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Isolation and Properties of Fungal β-Glucosidases

O. G. Korotkova1, M. V. Semenova2, V. V. Morozova2*, I. N. Zorov1,2, L. M. Sokolova3, T. M. Bubnova3, O. N. Okunev3, and A. P. Sinitsyn1,2

1Bach Institute of Biochemistry, Russian Academy of Sciences, Leninskii pr. 33/2, 119071 Moscow, Russia; fax: (495) 954-2732

2Chemical Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia; fax: (495) 939-0997; E-mail: valeria.morozova@gmail.com

3Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, 142292 Pushchino, Moscow Region, Russia; fax: (495) 923-3602

* To whom correspondence should be addressed.

Received May 22, 2008; Revision received June 19, 2008
Using chromatography on different matrixes, three β-glucosidases (120, 116, and 70 kDa) were isolated from enzymatic complexes of the mycelial fungi Aspergillus japonicus, Penicillium verruculosum, and Trichoderma reesei, respectively. The enzymes were identified by MALDI-TOF mass-spectrometry. Substrate specificity, kinetic parameters for hydrolysis of specific substrates, ability to catalyze the transglucosidation reaction, dependence of the enzymatic activity on pH and temperature, stability of the enzymes at different temperatures, adsorption ability on insoluble cellulose, and the influence of glucose on catalytic properties of the enzymes were investigated. According to the substrate specificity, the enzymes were shown to belong to two groups: i) β-glucosidase of A. japonicus exhibiting high specific activity to the low molecular weight substrates cellobiose and pNPG (the specific activity towards cellobiose was higher than towards pNPG) and low activity towards polysaccharide substrates (β-glucan from barley and laminarin); ii) β-glucosidases from P. verruculosum and T. reesei exhibiting relatively high activity to polysaccharide substrates and lower activity to low molecular weight substrates (activity to cellobiose was lower than to pNPG).
KEY WORDS: β-glucosidase, Aspergillus japonicus, Penicillium verruculosum, Trichoderma reesei, saccharification, transglucosidation, HPLC

DOI: 10.1134/S0006297909050137