title: Characterization of a novel arabinose-tolerant α-L-arabinofuranosidase with high ginsenoside Rc to ginsenoside Rd bioconversion productivity.
abstract: OBJECTIVE
  (i) To investigate the enzymatic characterization of α-L-arabinofuranosidase from Thermotoga thermarum DSM5069. (ii) To evaluate the performance of its excellent properties on converting ginsenoside Rc to ginsenoside Rd.
  
  
  RESULTS
  The thermostable α-L-arabinofuranosidase (Tt-Afs) gene from T. thermarum DSM5069 was cloned and overexpressed. Recombinant Tt-Afs was purified, and its molecular weight was approx. 55 kDa. Its optimal activity was at pH 5·0 and 95°C. It has high selectivity for cleaving the outer arabinofuranosyl moieties at the C-20 carbon of ginsenoside Rc and its sugar-tolerance makes Tt-Afs a promising candidate for the production of ginsenoside Rd. In a reaction at 85°C and pH 5·0, 25 g l(-1) of ginsenoside Rc was transformed into 21·8 g l(-1) of Rd within 60 min, with a corresponding molar conversion of 99·4% and a high ginsenoside Rd productivity of 21800 mg l(-1) h(-1).
  
  
  CONCLUSIONS
  We have successfully cloned and overexpressed the novel α-l-arabinofuranosidase from T. thermarum DSM5069. The high ginsenoside Rd productivity and detailed characterization of recombinant Tt-Afs was provided.
  
  
  CONCLUSIONS
  The result shows a high productivity on the bioconversion from high concentration ginsenoside Rc to ginsenoside Rd, which also give rise to a potential commercial enzyme application.
authors.affiliation: College of Chemical Engineering, Nanjing Forestry University, Nanjing, China.
authors.forename: J
authors.initials: J
authors.lastname: Xie
authors.affiliation: College of Chemical Engineering, Nanjing Forestry University, Nanjing, China.
authors.forename: D
authors.initials: D
authors.lastname: Zhao
authors.affiliation: College of Chemical Engineering, Nanjing Forestry University, Nanjing, China.|Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals, Nanjing, China.
authors.forename: L
authors.initials: L
authors.lastname: Zhao
authors.affiliation: College of Chemical Engineering, Nanjing Forestry University, Nanjing, China.|Jiangsu Key Laboratory of Biomass Based Green Fuels and Chemicals, Nanjing, China.
authors.forename: J
authors.initials: J
authors.lastname: Pei
authors.affiliation: Jiangsu Kanion Pharmaceutical Co., Ltd., Lianyungang, China.
authors.forename: W
authors.initials: W
authors.lastname: Xiao
authors.affiliation: Jiangsu Kanion Pharmaceutical Co., Ltd., Lianyungang, China.
authors.forename: G
authors.initials: G
authors.lastname: Ding
authors.affiliation: Jiangsu Kanion Pharmaceutical Co., Ltd., Lianyungang, China.
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.affiliation: University of Massachusetts Lowell, Lowell, MA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Xu
mesh_terms: D001089:Arabinose / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001711:Biotransformation; D004795:Enzyme Stability; D036145:Ginsenosides / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006089:Gram-Negative Anaerobic Bacteria / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D008970:Molecular Weight; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D036145:Ginsenosides; C044462:ginsenoside Rc; D001089:Arabinose; D006026:Glycoside Hydrolases; C019713:alpha-N-arabinofuranosidase; C049863:ginsenoside Rd
keywords: Thermotoga thermarum DSM5069; biotransformation; enzymatic characterization; ginsenoside Rd preparation; recombinant α-arabinofuranosidase