[Preparation and identification of DNA G-quadruplex antibody].

OBJECTIVE:To construct a prokaryotic expression plasmid of DNA G-quadruplex antibody, express it in E.coli BL21 (DE3) bacterial expression system, purify and identify the antibody. METHODS:Chemically synthesized BG4 gene of DNA G-quadruplex antibodies was inserted into pSANG10 plasmid to construct DNA G-quadruplex antibody expression vector pSANG10-BG4. BL21 (DE3) as the host strain was utilized for self-induced expression of the protein. Osmotic lysis method was used for collecting this protein. Thereafter, the protein was purified by histidine tag affinity chromatography and identified by SDS-PAGE and Western blotting. The function of this protein was verified in SW480 colon cancer cells. RESULTS:Double enzyme digestion and gene sequencing confirmed that DNA G-quadruplex antibody expression vector was successfully constructed. The relative molecular mass (Mr) of this protein was 30 000 to 37 000. The protein in a soluble form was expressed in the periplasm of BL21. The protein was of the same size as expected. CONCLUSION:The DNA G-quadruplex antibody has been successfully prepared.