title: Expression and characterization of a novel β-glucosidase, with transglycosylation and exo-β-1,3-glucanase activities, from Rhizomucor miehei.
abstract: A novel β-glucosidase gene, designated RmBglu3B, was cloned from the thermophilic fungus, Rhizomucor miehei CAU432. Its 2196-bp open reading frame encoded 731 amino acids. Its deduced amino-acid sequence showed highest identity (66%) with a glycoside hydrolase family 3 β-glucosidase from R. miehei NRRL5382. RmBglu3B was successfully expressed in Escherichia coli. The recombinant enzyme was purified to homogeneity with 18.2-fold purification and 59% recovery yield. Molecular masses of 76.5 kDa, by SDS-PAGE, and 66.4 kDa, by gel filtration, suggested that it is a monomer. Optimal pH and temperature of the purified enzyme were 5.0 and 50°C, respectively. RmBglu3B exhibited a broad range of substrate specificity, catalyzing the cleavage of β-1,2, β-1,3, β-1,4 and β-1,6 linkages, in various oligosaccharides, to liberate glucose. RmBglu3B also showed relatively high activity (19.1 U/mg) toward laminaran and transglycosylation activity, enabling gentiobiose production. This enzyme is a potential candidate for several industrial applications.
authors.affiliation: Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Bioresource Utilization Laboratory, College of Engineering, China Agricultural University, Beijing 100083, China.
authors.forename: Qiaojuan
authors.initials: Q
authors.lastname: Yan
authors.affiliation: Animal Science and Technology College, Beijing University of Agriculture, Beijing 102206, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yang
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.affiliation: Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China. Electronic address: zhqjiang@cau.edu.cn.
authors.forename: Zhengqiang
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D000595:Amino Acid Sequence; D043326:Glucan 1,3-beta-Glucosidase / Q000096:biosynthesis* / Q000737:chemistry*; D008969:Molecular Sequence Data; D020103:Rhizomucor / Q000201:enzymology*; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000096:biosynthesis* / Q000737:chemistry*
chemical_list: D001617:beta-Glucosidase; D043326:Glucan 1,3-beta-Glucosidase; C117648:beta-1,3-exoglucanase
keywords: Gene cloning; Gentiobiose; Laminaran; Rhizomucor miehei; Transglycosylation; β-Glucosidase