title: Characterization of a thermostable glycoside hydrolase (CMbg0408) from the hyperthermophilic archaeon Caldivirga maquilingensis IC-167.
abstract: BACKGROUND
  Hyperthermophilic archaea capable of functioning optimally at very high temperatures are a good source of unique and industrially important thermostable enzymes.
  
  
  RESULTS
  A glycoside hydrolase family 1 β-galactosidase gene (BglB) from a hyperthermophilic archaeon Caldivirga maquilingensis IC-167 was cloned and expressed in Escherichia coli. The recombinant enzyme (CMbg0408) displayed optimum activity at 110 °C and pH 5.0. It also retained 92% and 70% of its maximal activity at 115 and 120 °C, respectively. The enzyme was completely thermostable and active after 120 min of incubation at 80 and 90 °C. It also showed broad substrate specificity with activities of 8876 ± 185 U mg-1for p-nitrophenyl-β-d-galactopyranoside, 4464 ± 172 U mg-1for p-nitrophenyl-β-d-glucopyranoside, 1486 ± 68 U mg-1for o-nitrophenyl-β-d-galactopyranoside, 2250 ± 86 U mg-1for o-nitrophenyl-β-d-xylopyranoside and 175 ± 4 U mg-1for lactose. A catalytic efficiency (kcat/Km) of 3059 ± 122 mmol L-1s-1and Kmvalue of 8.1 ± 0.08 mmol L-1were displayed towards p-nitrophenyl-β-d-galactopyranoside.
  
  
  CONCLUSIONS
  As a result of its remarkable thermostability and high activity at high temperatures, this novel β-galactosidase may be useful for food and pharmaceutical applications. © 2016 Society of Chemical Industry.
authors: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China.|National Food Technology Research Centre, Private Bag 008, Kanye, Botswana.
authors: Rebaone
authors: R
authors: Letsididi
authors: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China.
authors: Hinawi Am
authors: HA
authors: Hassanin
authors: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China.
authors: Marwa Yf
authors: MY
authors: Koko
authors: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China.
authors: Jean B
authors: JB
authors: Ndayishimiye
authors: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China.|Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China.
authors: Tao
authors: T
authors: Zhang
authors: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China.|Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China.
authors: Bo
authors: B
authors: Jiang
authors: University of Hohenheim, Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, Garbenstrasse 25, 70599, Stuttgart, Germany.
authors: Timo
authors: T
authors: Stressler
authors: University of Hohenheim, Institute of Food Science and Biotechnology, Department of Biotechnology and Enzyme Science, Garbenstrasse 25, 70599, Stuttgart, Germany.
authors: Lutz
authors: L
authors: Fischer
authors: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, 214122, China.|Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi, 214122, China.
authors: Wanmeng
authors: W
authors: Mu
mesh_terms: D001105:Archaea / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004795:Enzyme Stability; D005690:Galactose / Q000378:metabolism; D005960:Glucosides / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D007785:Lactose / Q000378:metabolism; D013379:Substrate Specificity; D001616:beta-Galactosidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D005960:Glucosides; C025193:4-nitrophenyl beta-D-glucoside; D001616:beta-Galactosidase; D007785:Lactose; D005690:Galactose
keywords: Caldivirga maquilingensis; glycoside hydrolase; hyperthermophilic; thermostability; β-galactosidase