Prokaryotic Expression, Purification And Activity Assay Of Human Polypeptide: N-acetylgalactosaminyltransferase2

Objective: To express the full-length encoding sequence of human polypeptide: N-Acetylgalactosaminyltransferase2 in Escherichia coli using vector pGEX-5X-3. Analyze its enzyme activity after purification and renaturation. Methods: The cDNA gene encoding ppGalNAc-T2, which was amplified from plasmid pDONR201-T2 by PCR, was subcloned into prokaryotic expression vector pGEX-5X-3, resulting in the recombinant plasmid pGEX-5X-3/T2 which was subsequently transformed into Escherichia coli BL21. Then a fusion protein was expressed after the induction by IPTG. After testified by western blot, we purified the expression products by Glutathione-Sepharose affinity chromatography. After renaturation, its enzyme activity was assayed by Reverse Phase High Performance Liquid Chromatography (RP-HPLC). Results: The plasmid pGEX-5X-3/T2 was reconstructed successfully. The fusion protein was expressed and testified by SDS-PAGE and western blot. The purified enzyme was obtained by affinity chromatography and the HPLC showed its activity. Conclusion: The ppGalNAc-T2 which has certain enzyme activity was successfully expressed and purified in our research. This established a foundation for the further research in multiclonal antibody preparation and protein crystallization.