en 27920886 <p>Background: In the recent years, there has been an increasing interest in secretory production of recombinant proteins, due to its various advantages compared with intracellular expression. Signal peptides play a critical role in prosperous secretion of recombinant proteins. Accordingly, different signal peptides have been assessed for their ability to produce secretory proteins by trial-and-error experiments. The aim of this study was to evaluate the effect of L-asparaginase II signal peptide on the recombinant human Growth Hormone (hGH) protein secretion in the <em>Escherichia coli (E. coli)</em> host.<br /> Methods: Cloning and expression of a synthetic hGH gene, containing L-asparaginase II signal sequence was performed in <em>E. coli</em> BL21 (DE3) using 0.1 <em>mM</em> IPTG as an inducer at 23^o<em>C</em> overnight. Periplasmic protein extraction was performed using three methods, including osmotic shock, osmotic shock in the presence of glycine and combined Lysozyme/EDTA osmotic shock. Afterwards, the hGH expression was determined by SDS-PAGE.<br /> Results: Based on experimentally obtained results, hGH protein is expressed as inclusion body even in the presence of L-asparaginase II signal peptide.<br /> Conclusion: Therefore, this signal peptide is not effective for secretory production of the recombinant hGH.</p> Escherichia coli (E. coli), Human growth hormone, L-asparaginase II, Recombinant proteins, Signal peptide 182 187 https://www.ajmb.org/En/Article.aspx?id=255 https://www.ajmb.org/PDF/En/FullText/255.pdf MozhdehZamaniDepartment of Pharmaceutical Biotechnology, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran1040NavidNezafatPharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran1041YounesGhasemiDepartment of Pharmaceutical Biotechnology, Faculty of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran1042