title: Optimized expression, purification and characterization of a family 11 xylanase (AuXyn11A) from Aspergillus usamii E001 in Pichia pastoris.
abstract: BACKGROUND
  Xylanases have attracted much attention because of their potential applications. Unfortunately, the commercialization of xylanases is limited by their low catalytic activities. The aim of this study was to improve the activity of a xylanase by optimization of the expression conditions and to investigate its characterization.
  
  
  RESULTS
  The activity of recombinant AuXyn11A (reAuXyn11A), a family 11 xylanase from Aspergillus usamii E001 expressed in Pichia pastoris GS115, reached 912.6 U mL⁻¹ under the optimized conditions, which was 2.14 times as high as that expressed using the standard protocol. After the endogenous 18-aa propeptide had been processed in P. pastoris, reAuXyn11A (188-aa mature peptide) was secreted and purified with a specific activity of 22 714 U mg⁻¹. It displayed maximum activity at pH 5 and 50 °C and was stable in the pH range 4-8 and at a temperature of 45 °C or below. Its activity was not significantly affected by most metal ions and EDTA. Xylooligosaccharides ranging from xylobiose (X2) to xylohexaose (X6) were produced from insoluble corncob xylan by reAuXyn11A.
  
  
  CONCLUSIONS
  Its high specific activity and good enzymatic properties suggest that reAuXyn11A is a potential candidate for applications in industrial processes.
authors.affiliation: School of Food Science and Technology, Jiangnan University, Wuxi, 214122, China; Key Laboratory of Carbohydrate Chemistry & Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China.
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Zhang
authors.forename: Jun-Qing
authors.initials: JQ
authors.lastname: Wang
authors.forename: Min-Chen
authors.initials: MC
authors.lastname: Wu
authors.forename: Shu-Juan
authors.initials: SJ
authors.lastname: Gao
authors.forename: Jian-Fang
authors.initials: JF
authors.lastname: Li
authors.forename: Yan-Jun
authors.initials: YJ
authors.lastname: Yang
mesh_terms: D001230:Aspergillus / Q000201:enzymology*; D004187:Disaccharides / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D004792:Enzyme Precursors / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D004795:Enzyme Stability; D005524:Food Technology; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008970:Molecular Weight; D010843:Pichia / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D059748:Proteolysis; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D055571:Secretory Pathway; D013379:Substrate Specificity; D014990:Xylans / Q000378:metabolism
chemical_list: D004187:Disaccharides; D004792:Enzyme Precursors; D005656:Fungal Proteins; D011994:Recombinant Proteins; D014990:Xylans; D043364:Endo-1,4-beta Xylanases; C004173:xylobiose
keywords: Aspergillus usamii; Pichia pastoris; optimized expression; purification; xylanase