title: Biochemical properties of a novel glycoside hydrolase family 1 β-glucosidase (PtBglu1) from Paecilomyces thermophila expressed in Pichia pastoris.
abstract: A novel β-glucosidase gene (PtBglu1) from the thermophilic fungus, Paecilomyces thermophila, was cloned and expressed in Pichia pastoris. PtBglu1 contained an open reading frame of 1440-bp nucleotides and encoded a protein of 479 amino acids which showed significant similarity to other fungal β-glucosidases from glycoside hydrolase (GH) family 1. The recombinant β-glucosidase (PtBglu1) was secreted at high level of 190.2 U mL(-1) in high cell density fermentor (5L). PtBglu1 was purified to homogeneity, and was found to be a glycoprotein with molecular mass of 56.7 kDa. The purified PtBglu1 showed optimum catalytic activity at pH 6.0 and 55 °C. The enzyme exhibited broad substrate specificity with highest activity toward pNP-β-D-glucopyranoside, followed by pNP-β-D-galactopyranoside and cellobiose. The K(m) values for pNP-β-D-glucopyranoside, cellobiose, gentiobiose and salicin were 0.55 mM, 1.0 mM, 1.74 mM and 6.85 mM, respectively. These properties make PtBglu1 a potential candidate for various industrial applications.
authors.affiliation: Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
authors.forename: Shaoqing
authors.initials: S
authors.lastname: Yang
authors.forename: Chengwei
authors.initials: C
authors.lastname: Hua
authors.forename: Qiaojuan
authors.initials: Q
authors.lastname: Yan
authors.forename: Yinan
authors.initials: Y
authors.lastname: Li
authors.forename: Zhengqiang
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D004926:Escherichia coli; D015870:Gene Expression; D007700:Kinetics; D008969:Molecular Sequence Data; D010143:Paecilomyces / Q000201:enzymology*; D010843:Pichia / Q000201:enzymology / Q000235:genetics; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D001617:beta-Glucosidase