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

Abstract

Extracellular xylanase XYNB fromStreptomyces olivaceoviridis A1 has been purified and characterized. The optimal pH value and temperature of XYNB for its activity are 5.2 and 60°C, 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 genexynB 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 genexynB is 576 bp long and its G+C content is 64.3%. ThexynB encodes 191 amino acid residues, and the putative molecular weight of XYNB is 20.839 kD. ThexynB has been expressed inE. coli, and the expressed xylanase has normal bioactivity.