[Construction, expression and refolding of recombinant luteinizing hormone releasing hormone-angiogenin toxin].

ABSTRACT

OBJECTIVE: To express, purify and refold recombinant luteinizing hormone releasing hormone-angiogenin (LHRH-Ang) toxin using E. coli. expression system. METHODS: Recombinant LHRH-Ang expression vector was constructed by replacing of EGF fragment in plasmid pET28a/EGF-Ang with LHRH-PII fragment amplified from plasmid pET28/MSH-PE40. DNA sequencing would be used to verify the correction of fused LHRH-PII-Ang gene. Then, E. coli strain BL21 (DE3) was transformed by pET28a/LHRH-Ang vector. Expression of recombinant LHRH-Ang toxin was induced by Isopropyl-ß-D-Thiogalactoside (IPTG). Refolding effects of gradient dialysis was evaluated by SDS-PAGE. RESULTS: Prokaryotic expression vector pET28a/LHRH-Ang, containing LHRH-PII-Ang fusion gene, was constructed by PCR amplification, restriction enzyme digestion and ligation method. Sequence correction of fusion gene was confirmed by DNA sequencing. After IPGT induction, recombinant LHRH-Ang protein was expressed in BL21 (DE3) as inclusion body, it took 18.43% of total protein. Inclusion body was resolved in 8 mol/L urea and purified by DEAE-Sepharose FF column, the purity was 85%. Recombinant LHRH-Ang toxin was refolded and concentrated by gradient dialysis and PEG 20000, respectively. CONCLUSIONS: Recombinant LHRH-Ang protein was expressed in E. coli and refolded successfully.