Overexpression, purification and characterization of recombinant salmon calcitonin, a therapeutic protein, in Streptomyces avermitilis.

Calcitonin (CT) is a peptide hormone produced by the parafollicular cells of the thyroid gland in mammals and by the ultimobranchial gland of birds and fish. Salmon calcitonin (sCT), which is more potent and longer lasting than human CT, has been used widely for the treatment of osteoporosis, paget's disease, hypercalcemic shock and chronic pain in terminal cancer patients. sCT is one of the many bioactive peptides that require C-terminal amidation for full biological activity. In this study we describe the over-expression and over-production of C-terminal amidated sCT in recombinant Streptomyces avermitilis. With this approach the utilization of expensive peptide synthesis can be circumvented.