title: Expression and characterization of a GH43 endo-arabinanase from Thermotoga thermarum.
abstract: BACKGROUND
  Arabinan is an important plant polysaccharide degraded mainly by two hydrolytic enzymes, endo-arabinanase and α-L-arabinofuranosidase. In this study, the characterization and application in arabinan degradation of an endo-arabinanase from Thermotoga thermarum were investigated.
  
  
  RESULTS
  The recombinant endo-arabinanase was expressed in Escherichia coli BL21 (DE3) and purified by heat treatment followed by purification on a nickel affinity column chromatography. The purified endo-arabinanase exhibited optimal activity at pH 6.5 and 75°C and its residual activity retained more than 80% of its initial activity after being incubated at 80°C for 2 h. The results showed that the endo-arabinanase was very effective for arabinan degradation at higher temperature. When linear arabinan was used as the substrate, the apparent K(m) and V(max) values were determined to be 12.3 ± 0.15 mg ml⁻¹ and 1,052.1 ± 12.7 μmol ml⁻¹ min⁻¹, respectively (at pH 6.5, 75°C), and the calculated kcat value was 349.3 ± 4.2 s⁻¹.
  
  
  CONCLUSIONS
  This work provides a useful endo-arabinanase with high thermostability andcatalytic efficiency, and these characteristics exhibit a great potential for enzymatic conversion of arabinan.
authors.forename: Hao
authors.initials: H
authors.lastname: Shi
authors.forename: Huaihai
authors.initials: H
authors.lastname: Ding
authors.forename: Yingjuan
authors.initials: Y
authors.lastname: Huang
authors.forename: Liangliang
authors.initials: L
authors.lastname: Wang
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xun
authors.initials: X
authors.lastname: Li
authors.affiliation: College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China. hgwf@njfu.edu.cn.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D002846:Chromatography, Affinity; D004926:Escherichia coli / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D016965:Gram-Negative Anaerobic Straight, Curved, and Helical Rods / Q000201:enzymology* / Q000235:genetics*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D011134:Polysaccharides; D011994:Recombinant Proteins; C030080:araban; C074451:Endo-arabinase; D006026:Glycoside Hydrolases