The GFP(green fluorescence protein)-streptavidin(SA) bi-functional fusion protein was generated and characterized in order to demonstrate novel platform for efficiently and durably modifying the cell surface with SA-tagged bi-functional proteins.The GFP-SA/pET24d construct was generated and expressed in BL21(DE3) host bacteria at the high level.The recombinant protein GFP-SA was purified through the Ni-NTA affinity chromatography,and then refolded.After biotinylation B16 tumor cells were modified with GFP-SA bi-functional fusion protein and then subjected to fluorescent microscopy and FACS analysis.The effect of surface modification on the viability and growth of B16.F10 tumor cells was evaluated by MTT staining.The GFP-SA recombinant fusion protein was expressed in BL21(DE3) at about 20 % of total bacterial proteins.The GFP-SA bi-functional fusion protein exhibited the bi-functionality,i.e.,SA-mediated high-affinity binding to biotinylated cell surfaces and GFP-emitted green fluorescence.The cell surface modification with GFP-SA bi-functional fusion protein did not affect the viability and growth of the modified B16.F10 tumor cells significantly.The GFP-SA bi-functional fusion protein was obtained and could be displayed efficiently on the surface of the biotinylated B16.F10 tumor cells through the specific and tight interaction between streptavidin and biotin,thus can be used as good trace protein and experimental control in the development of surface-modified tumor vaccine.

Objective To study the purification and renaturation of recombinant human IL-2/GM-CSF fusion protein. Methods After the inclusion bodies were isolated, the optimal conditions of denaturation and renaturation were studied. The renatured recombinant human IL-2/GM-CSF was purified by DEAE-Sepharose FF ion-exchange chromatography. Results The purified product manifested biological activity with purity of up to 95%. Conclusions The procedures employed in this study is simple and reliable.

Objective To study the purification and renaturation of recombinant human IL-2/GM-CSF fusion protein. Methods After the inclusion bodies were isolated, the optimal conditions of denaturation and renaturation were studied. The renatured recombinant human IL-2/GM-CSF was purified by DEAE-Sepharose FF ion-exchange chromatography. Results The purified product manifested biological activity with purity of up to 95%. Conclusions The procedures employed in this study is simple and reliable.