Glycine-aspartic _ acid-serine-leucine esterase Xcc_ est from Xanthomonas campestris pv. campestris 8004 and its esterase domain: gene expression in Escherichia coli, refolding and characterization
野油菜黄单胞菌8004甘天丝亮特征序列酯酶及其酯酶结构域在大肠杆菌中的表达，包涵体复性及性质

Objective] To characterize the GDSL (glycine, aspartic acid, serine and leucine motif in protein sequence) esterase Xcc_ est from Xanthomonas campestris pv. campestris (Xcc) 8004. Methods] Xcc _ est gene and different domains of Xcc _ est gene were PCR amplified and expressed in Escherichia coli, the HIS-Tagged fusion proteins were pttrified by Ni-NTA chromatography. Results] The optimum pH and temperature of partly purified Xcc_ est were 8.0 and 52℃ when pNPB (4-nitrophonylbutyrate) was used as substrate. The Km and Vmax value of Xcc _ est and the passenger domain (Xcc _ estN1-334) for pNPB were 47.6±4.6 mol/L, 67.6±7.8 U/mg and 469.4 ±9.8 mol/L, 2.5±0.9 U/mg respectively. Inclusion bodies of mature domain Xcc _ est (Xcc _ estN26-606) could be refolded but inclusion bodies of the passenger domain (Xcc _ estN26-334) could not be refolded. Refolded mature domain had broad substrate spectrum and showed higher stability than Xcc_ est when stored at 25 ℃. Conclusions] Refolded Xcc_ estN26-606 can be a candidate for biotransformation application.