Leptin, a peptide hormone, is produced by mature adipocytes and functions primarily in the hypothalamus to reduce food intake and body weight. Recombinant h-leptin has been shown to be effective in obesity treatment. To overexpression of recombinant human leptin in Escherichia coli, the human leptin gene (hob gene) was cloned into the vector pET-28a. When analysis expression of human leptin in E. coli BL21(DE3) strain, it was found that recombinant vector pET-hob expressed h-leptinproteins in cytoplasm, and mainly as insoluble inclusion bodies. This result will be the premise for researching to produce recombinant human leptin protein.

hG-CSF is a cytokine that stimulates the proliferation, differentiation, function of mature neutrophils and is generally used for treatment of neutropenia in cancer patients under chemotherapy or other diseased patients. After production process, E. coli-derived recombinant hGCSF is usually available as non-glycosylated, liquid protein, so that it’s often unstable, easy to lose their biological activity. In this study, we report the results of using lyophilization to storage recombinant hG-CSF. We found out the freezing conditions and the suitable protein volumes for freezedrying process. Furthermore, we also studied the effects of lyophilization on this protein by testing the structure with Native-PAGE, RP-HPLC, testing biological activity on M-NFS-60 cell lines and in mouse (Mus musculus).