Abstract：Having known the Xyn II cDNA sequence (Genbank accession number DQ114485),a pair of primers (with the EcoR I and Sal I sites) were designed.With the recombinant plasmid pUCm-T-xyn II as a template,Xyn II cDNA fragment (555 bp) encoding mature peptide was then amplified,inserted into the plasmid pET-28a.The resultant recombinant plasmid pET-28a- xyn II was transformed into E. coli BL21- CodonPlus(DE3)-RIL,and finally the recombinant strain B21/xyn II was obtained.Induced by IPTG,a maximum activity of 35.6 U/mg was obtained from cellular extract of E. coli B21/xyn II.The recombinant protein was purified by immobilizing metal affinity chromatography.The optimum temperature and pH for recombinant enzyme were 45℃ and 4.6,respectively.
