Characterization,gene cloning and expression of new xylanase XYNB with high specific activity

Extracellular xylanase XYNB from Streptomyces olivaceoviridis A1 has been purified and characterized. The optimal pH value and temperature of XYNB for its activity are 5.2 and 60℃, respectively. The specific activity of XYNB is as high as 2869.78 U/mg. Metal cations, EDTA and SDS have no effects on enzyme activity of XYNB. The gene xynB coding mature protein of XYNB has been cloned by PCR. The forward oligonucleotide primer used in the PCR reaction was synthesized based on the N-terminal amino acid sequence of XYNB mature protein, and the reverse oligonucleotide primers are random oligonucleotide. The cloned gene xynB is 576 bp long and its G+C content is 64.3%. The xynB encodes 191 amino acid residues, and the putative molecular weight of XYNB is 20.839 kD. The xynB has been expressed in E. coli, and the expressed xylanase has normal bioactivity.