HIGH EXPRESSION OF A RECOMBINANT HUMAN CALCITONIN PRECURSOR PEPTIDE IN ESCHERICHIA-COLI

Human calcitonin (hCT) is a C-terminus a-amidated peptide hormone cons isting of 32 amino acids. The amidated structure is essential for its biological activities, and the C-terminal-glycine-extended precursor p eptide, hCT[G], is converted to bioactive hCT by a C-terminus-a-amidat ing enzyme. An efficient production method is described for the hCT[G] peptide, as a part of the fusion protein consisting of a modified E. coli P-galactosidase, linker amino acids and hCT[G]. Stable inclusion bodies of the fusion protein in E. coli were expressed by focusing on the amino acid charge, and the fusion protein was modified by insertin g a basic amino acid sequence into its linker region. This modificatio n greatly affected the formation of inclusion bodies. E. coli strain W 3110/pG97S4DhCT [G]R4 could produce a large amount of stable inclusion bodies, and the hCT[G] peptide was released quantitatively from the f usion protein by S. aureus V8 protease. This enabled a large-scale pro duction method to be established for the hCT[G] precursor peptide in E . coli to produce mature hCT.