title: Expression and characterization of a new thermostable esterase from Clostridium thermocellum.
abstract: The thermostable esterase from the thermophilic bacterium Clostridium thermocellum DSM 1313 was expressed in Escherichia coli and purified by Ni(2+) affinity chromatography. Its molecular weight was approximately 35 kDa according to 12 % sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis. The enzyme exhibited the highest specific activity with p-nitrophenyl butyrate (285 s(-1) mM(-1)). The activity of the esterase was greatest at 65 °C, and the esterase maintained residual activity levels of 70 and 50 % after 3 h incubation at 65 and 70 °C, respectively. Its activity was optimal at pH 7.0, was enhanced in the presence of Ca(2+) and Mg(2+), and was inhibited by Ni(2+) and Cu(2+). The addition of surfactants, such as Tween-20, Tween-80, Triton X-100, and SDS, at concentrations of 5 % (v/v) significantly inhibited the lipolytic action of the esterase. Enzyme activity was relatively stable in 10 % methanol, and 50 % residual activity was seen in 10 % DMSO, demonstrating its potential in biodiesel production and industrial applications.
authors.affiliation: Institute of Life Sciences, Jiangsu University, Zhenjiang, 212013, China.
authors.forename: Tianxi
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Institute of Life Sciences, Jiangsu University, Zhenjiang, 212013, China. hyc@ujs.edu.cn.|National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 10090, China. hyc@ujs.edu.cn.|Division of Biological Sciences, University of California at San Diego, La Jolla, CA, 92093-0116, USA. hyc@ujs.edu.cn.
authors.forename: Huayou
authors.initials: H
authors.lastname: Chen
authors.affiliation: Institute of Life Sciences, Jiangsu University, Zhenjiang, 212013, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Ni
authors.affiliation: Institute of Life Sciences, Jiangsu University, Zhenjiang, 212013, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Tian
authors.affiliation: Institute of Life Sciences, Jiangsu University, Zhenjiang, 212013, China.
authors.forename: Jinru
authors.initials: J
authors.lastname: Jia
authors.affiliation: Institute of Life Sciences, Jiangsu University, Zhenjiang, 212013, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Institute of Life Sciences, Jiangsu University, Zhenjiang, 212013, China.
authors.forename: Shengli
authors.initials: S
authors.lastname: Yang
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D048013:Acetivibrio thermocellus / Q000201:enzymology* / Q000235:genetics*; D004795:Enzyme Stability; D004950:Esterases / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D008670:Metals / Q000494:pharmacology; D008969:Molecular Sequence Data; D013696:Temperature
chemical_list: D008670:Metals; D004950:Esterases
keywords: Characterization; Clostridium thermocellum; Esterase; Expression; Thermostable