Abstract: For investigating the activity and biological functions of glucosyltransferase in Nicotiana tabacum, gene NtGT5a was cloned from tobacco cultivars.By referring to the nucleotide sequence of NtGT5a of Nicotiana tabacum published on GenBank(GenBank accession number AB176523),specific primers were designed and synthesized.The cDNA fragment of NtGT5a was obtained with RT-PCR by using the total RNA from leaves of cv.Honghuadajinyuan as template.Sequence analysis showed that the gene contained a full coding region of 1458 bp,encoded 485 amino acid residues with the estimated protein molecular mass of 54.21 kDa and the theoretical isoelectric point of 5.41.The coding sequence of NtGT5a gene was cloned into the prokaryotic expression vector pCold-SUMO,and this construct was expressed in E.coli BL21(DE3).The recombinant protein SUMO-NtGT5a was generated via 0.2 mmol/L IPTG(isopropyl-β-D-thiogalactopyranoside) induction at 15℃ for 22 hours.Part of the recombinant protein was presented in the form of soluble protein and the other in the form of inclusion body.The supernatant containing the soluble target protein was purified by Ni-NTA column chromatography and gel filtration chromatography.The fusion tag was further removed by the SUMO protease,and the target recombinant protein NtGT5 of high purity was obtained by repurification with Ni-NTA column chromatography.