Investigation on Cloning and Expression of Recombinant Human Parathyroid Hormone in Lab-Scale

Preserving the level of calcium concentration in the blood is a dynamic process that is carried out through the interaction of several organs such as the intestine, kidney, and parathyroid glands. Human parathyroid hormone (hPTH) increases blood calcium level by increasing intestinal absorption of calcium and decreasing renal excretion. Therefore, this hormone is used for the treatment of osteoporosis and diseases of the disorders in parathyroid gland function. In this research, the plasmid pUC 57 and strain of E.coli DH5α are used for cloning and the plasmid pET 32a (+) and strain of E.coli BL21 are used for protein expression. In this study, protein production was carried out in a 1 L batch Erlenmeyer and in a 10 L fed-batch mixed bioreactor. The results of this research showed that the amounts of biomass and recombinant human parathyroid hormone were about 6.5 g/l and 1.7 g/l in shake flasks after 16 h. Also, our results showed the amounts of biomass and recombinant human parathyroid hormone were about 81 g/l and 22 g/l in the fed-batch bioreactor after 12 h, respectively. Finally, the production of recombinant human parathyroid hormone was confirmed by SDS-PAGE and western blot analyses. However, in this research, the presence of a protein band in the 37 kDa region indicates the correct expression of the parathyroid hormone. According to the successful production of human parathyroid hormone in this study, as well as the advantages of Escherichia coli as a host, it seems that this method can be a good alternative to producing this valuable drug.