Objective: To enhance the solubility expression of carbonyl reductase ChKRED20 and investigate its enzymatic properties. Methods : The ChKRED20 gene was synthesized and transformed into Escherichia coli BL21(DE3) for heterologous expression. The solubility of the protein was evaluated by adding or removing His⁃tag ,changing its position , and adjusting the induction conditions. Further optimization was performed by varying the in⁃duction time , temperature and IPTG concentration. Subsequently , the enzymatic properties of the recombinant en⁃zyme were examined. Results: The ChKRED20 was cloned within the Escherichia coli system to achieve soluble protein expression . This was achieved by removing the His_tag and optimizing expression conditions . Compared to enzymes with the N_terminal and C _terminal His_tags , the enzyme activity of ChKRED20 without His_tag increased by 0. 77 and 1 . 28 times , respectively. The optimal temperature and pH for enzyme activity were 55 ℃ and 8. 0 , respectively. Furthermore , the enzyme demonstrated good adaptability in higher temperature and alkaline environ_ ments . Conclusion The removal of the His_tag and the optimization of expression conditions can significantly im_ prove the soluble expression of ChKRED20 in Escherichia coli .

Somatostatin (SST) is an inhibitory polypeptide hormone that plays an important role in a variety of biological processes. Somatostatin receptor 2 (SSTR2) is the most widely expressed somatostatin receptor. However, the specific cell types expressing Sstr2 in the tissues have not been investigated. In this study, we detected the expression pattern of SSTR2 protein in mouse at different development stages, including the embryonic 15.5 days and the postnatal 1, 7, 15 days as well as 3 and 6 months, by multicolour immunofluorescence analyses. We found that Sstr2 was expressed in some specific cells types of several tissues, including the neuronal cells and astrocytes in the brain, the mesenchymal cells, the hematopoietic cells, the early hematopoietic stem cells, and the B cells in the bone marrow, the macrophages, the type Ⅱ alveolar epithelial cells, and the airway ciliated cells in the lung, the epithelial cells and the neuronal cells in the intestine, the hair follicle cells, the gastric epithelial cells, the hematopoietic stem cells and the nerve fibre in the spleen, and the tubular epithelial cells in the kidney. This study identified the specific cell types expressing Sstr2 in mouse at different developmental stages, providing new insights into the physiological function of SST and SSTR2 in several cell types.
Mice ; Animals ; Receptors, Somatostatin/metabolism* ; Hematopoietic Stem Cells/metabolism* ; Epithelial Cells