title: Hydrolysis of Oligosaccharides by a Thermostable α-Galactosidase from Termitomyces eurrhizus.
abstract: The genus of Termitomyces purchased from the market has been identified as Termitomyces eurrhizus using the Internal Transcribed Spacer (ITS) method. An α-galactosidase from T. eurrhizus (TEG), a monomeric protein with a molecular mass of 72 kDa, was purified 146 fold by employing ion exchange chromatography and gel filtration. The optimum pH and temperature was 5.0 and 60 °C, respectively. TEG was stable over pH 2-6, and also exhibited good thermostablility, retaining 100% of the original activity after incubation at 60 °C for 2 h. Inhibition of the enzyme activity by N-bromosuccinimide (NBS) constituted evidence for an essential role of tryptophan in the catalytic action of the isolated enzyme. Besides 4-nitro-phenyl α-d-galactophyranoside (pNPGal), natural substrates could also be effectively hydrolyzed by TEG. Results of thin-layer chromatography (TLC) revealed complete enzymatic hydrolysis of raffinose and stachyose to galactose at 50 °C within 6 h. These properties of TEG advocate its utilization for elevating the nutritional value of soymilk.
authors.affiliation: State Key Laboratory for Agrobiotechnology and Department of Microbiology, China Agricultural University, Beijing 100193, China. lczww2003@cau.edu.cn.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Shaanxi Microbiology Research Institute, No. 76 Xiying Road, Xi'an 710043, China. duf35@163.com.
authors.forename: Fang
authors.initials: F
authors.lastname: Du
authors.affiliation: State Key Laboratory for Agrobiotechnology and Department of Microbiology, China Agricultural University, Beijing 100193, China. haoyou0102@163.com.
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.affiliation: College of Food Science and Technology, Nanjing Agricultural University, Weigang, Nanjing 210095, China. zhlychen@njau.edu.cn.
authors.forename: Liyan
authors.initials: L
authors.lastname: Zhao
authors.affiliation: State Key Laboratory for Agrobiotechnology and Department of Microbiology, China Agricultural University, Beijing 100193, China. hxwang@cau.edu.cn.
authors.forename: Hexiang
authors.initials: H
authors.lastname: Wang
authors.affiliation: School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. b021770@mailserv.cuhk.edu.hk.
authors.forename: Tzi Bun
authors.initials: TB
authors.lastname: Ng
mesh_terms: D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007477:Ions; D008670:Metals; D009844:Oligosaccharides / Q000737:chemistry*; D013379:Substrate Specificity; D013696:Temperature; D055434:Termitomyces / Q000201:enzymology*; D000519:alpha-Galactosidase / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D007477:Ions; D008670:Metals; D009844:Oligosaccharides; D000519:alpha-Galactosidase
keywords: ITS; TLC; Termitomyces eurrhizus; characterization; degradation