A novel highly thermostable xylanase stimulated by Ca2+ from Thermotoga thermarum: cloning, expression and characterization

摘要: Xylanase is an important component of hemicellulase enzyme system. Since it plays role in the hydrolysis hemicellulose into xylooligosaccharides (XOs), high thermostable xylanase has been focus much recent attention as powerful well field biomass utilization. A gene (xyn10A) with 3,474 bp was cloned from extremely thermophilic bacterium Thermotoga thermarum that encodes a protein containing 1,158 amino acid residues. Based on sequence homology, hydrophobic cluster and three dimensional structure analyses, attested belongs to glycoside hydrolase (GH) families 10 five carbohydrate binding domains. When expressed Escherichia coli BL21 (DE3), specific activity produced by recombinant strain up 145.8 U mg-1. The optimally active at 95°C, pH 7.0. In addition, exhibited thermostability over broad range 4.0-8.5 temperature 55-90°C upon addition 5 mM Ca2+. Confirmed Ion Chromatography System (ICS) analysis, end products beechwood xylan were xylose, xylobiose, xylotriose, xylotetraose, xylopentaose xylohexaose. T. one hyperthermophilic xylanases exhibits thermostability, thus, suitable candidate for generating XOs cellulosic materials such agricultural forestry residues uses prebiotics precursors further preparation furfural other chemicals.