Antimicrobial peptides are the most promising alternatives to antibiotics. However, the strategy of producing antimicrobial peptides by recombinant technology is complicated and expensive, which is not conducive to the large-scale production. Oxysterlin 1 is a novel type of cecropin antimicrobial peptide mainly targeting on Gram-negative bacteria and is of low cytotoxicity. In this study, a simple and cost-effective method was developed to produce Oxysterlin 1 in Escherichia coli. The Oxysterlin 1 gene was cloned into a plasmid containing elastin-like polypeptide (ELP) and protein splicing elements (intein) to construct the recombinant expression plasmid (pET-ELP-I-Oxysterlin 1). The recombinant protein was mainly expressed in soluble form in E. coli, and then the target peptide can be purified with a simple salting out method followed by pH changing. The final yield of Oxysterlin 1 was about 1.2 mg/L, and the subsequent antimicrobial experiment showed the expected antimicrobial activity. This study holds promise for large-scale production of antimicrobial peptides and the in-depth study of its antimicrobial mechanism.
Elastin ; Escherichia coli/genetics* ; Inteins ; Peptides/pharmacology* ; Pore Forming Cytotoxic Proteins ; Recombinant Fusion Proteins/genetics*

This study sought to clarify the distribution of HMGN2 in HeLa cells. The recombinant eukaryotic expression vectors pcDNA3. 1-myc-his-HMGN2 and pEGFP-N1-HMGN2 were constructed, and then were transfected into HeLa cells. immunocytochemistry staining indicated that HMGN2 were present not only in HeLa nucleus but also in the cytoplasm. The presence of HMGN2 was also detected in the culture supernatant by ELISA with rabbit anti-serum against HMGN2 and mouse anti-His6 monoclonal antibodies. The confocal microscope observation showed the same subcellular localization as that of immunocytochemistry staining. There results suggested that HMGN2 could be present in the nucleus and cytoplasm of HeLa cell as well as in the extracellular environment.
Animals ; Antibodies, Monoclonal ; HMGN2 Protein ; immunology ; metabolism ; pharmacology ; HeLa Cells ; Humans ; Mice ; Rabbits ; Recombinant Fusion Proteins ; biosynthesis ; pharmacology ; Transfection

OBJECTIVEGonadotropin releasing hormones (GnRH) regulate the expression of annexin 5 in Leydig cells, and annexin 5 is supposed to be a signal molecule in regulating testosterone secretion. This study aimed to investigate the function of annexin 5 in male reproduction by observing its effect on human sperm motility in vitro.

METHODSThe encoding sequence of rat annexin 5 was chemically synthesized and inserted into the HIS fusion expression vector pET28a. The expression of the fusion protein HIS-annexin 5 was induced by isopropyl-beta-D-thiogalactoside (IPTG) under the control of the T7 promoter, and the products were purified by affinity chromatography. The anticoagulant activity of annexin 5 was determined by the modified activated partial thromboplastin time (APTT) test. Semen samples from 15 donors were assigned to a control and an annexin 5 group, the latter treated with recombinant annexin 5 at the concentration of 10(-8) mol/L. Sperm motility and the percentage of grade a + b sperm were measured by computer-assisted semen analysis (CASA) after 20 and 60 min exposure, and the sperm ascending experiment was done after 20 min treatment.

RESULTSThe product of the synthesized target gene was 947 bp in length, and the inserted sequence corresponded to the published encoding sequence of rat annexin 5. The plasmid pET28a-annexin 5 was transformed into E. coli BL21(DE3) and IPTG induced a fusion protein with a relative molecular weight of about 36,000, a purity of 95% and a high anticoagulant activity. Compared with the control group, sperm motility and the percentage of grade a + b sperm were increased by 40% (P < 0.01) and 21% (P < 0.01), respectively, after 20 min treatment with annexin 5, but neither showed any significant improvement after 60 min. The sperm ascending altitude was remarkably elevated after annexin 5 treatment, with extremely significant difference from the control group (37.84 +/- 6.35 vs. 49.5 +/- 12.27, P < 0.01).

CONCLUSIONAn annexin 5 recombinant expression vector was successfully constructed. The protein annexin 5 can be efficiently expressed in E. coli and effectively improve human sperm motility in vitro.

Animals ; Annexin A5 ; genetics ; pharmacology ; Genetic Vectors ; Humans ; Male ; Plasmids ; Rats ; Recombinant Fusion Proteins ; genetics ; pharmacology ; Sperm Motility

To obtain sufficient purified and active fusion protein-hepatocyte-targeting peptide-human endostatin (HTP-rES), we studied the growth curve and the optimal induction timing of BL21/pET21b-HTP-rES. Different conditions of pH value, induction time, induction concentration and induction temperature were optimized by univariate analysis. After washing, refolding and purifying, the activity of fusion protein was identified by flow cytometry and 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT). Results show that the logarithmic growth phase of BL21/pET21b-HTP-rES was from 1.5 h to 3.5 h, the optimum expression conditions were pH 8.0, 0.06 mmol/L IPTG, at 42 ℃ for 5 h. The purity of inclusion bodies was up to 60% after washing. The purity of target protein was more than 95% after refolding and purification. Our findings provide the foundation for further biological activity and drug development.
Drug Delivery Systems ; Endostatins ; pharmacology ; Escherichia coli ; Hepatocytes ; drug effects ; Humans ; Inclusion Bodies ; Peptides ; pharmacology ; Recombinant Fusion Proteins

Carcinoma, Hepatocellular ; drug therapy ; Cell Line, Tumor ; Escherichia coli ; metabolism ; Green Fluorescent Proteins ; genetics ; metabolism ; pharmacology ; Humans ; Melitten ; genetics ; metabolism ; pharmacology ; Recombinant Fusion Proteins ; genetics ; metabolism ; pharmacology

OBJECTIVETo investigate the anti-HBV effect of fusion protein thymosin alpha1-interferon alpha (TA1-IFN) in vitro and to compare its effect with a combination of interferon alpha and thymosin alpha1.

METHODSAfter 2.2.15 cells were seeded for 24 hours, drugs of five serial concentrations (8000, 4000, 2000, 1000, 500 U/ml) were added to the wells, then the medium was changed every three days. After 2.2.15 cells were treated with drugs for 6 days, the medium was collected. The inhibitory rates on HBsAg and HBeAg were determined using Abbot kit, and the cytotoxicity of different drugs by means of MTT colorimetric assays was also observed.

RESULTSThe inhibitory rate of fusion protein on HBsAg, HBeAg was dose-dependent and reached the maximum at 8000 U/ml concentration. In the meantime, the inhibitory rates of fusion protein on HBsAg and HBeAg were 72.2% +/- 0.8% and 60.4% +/- 1.1% respectively, and the cell survival rate was 85.2% +/- 2.0%; In the corresponding concentration, the inhibitory rates of combination thymosin alpha 1 and interferon alpha on HBsAg and HBeAg were 40.0% +/- 0.7%, 34.5% +/- 3.2% respectively. The results showed significant statistical differences between them; cell survival rate 70.0% +/- 1.9%, and the difference of the results was also significant. Cytotoxicity of fusion protein was weaker than a combination of thymosin alpha 1 and interferon alpha.

CONCLUSIONFusion protein TA1-IFN exerted stronger anti-HBV effects in vitro. Its anti-HBV effects in vitro were stronger than the combination of thymosin alpha and interferon alpha, and its cytotoxicity was weaker than the combination of thymosin alpha and interferon alpha. Our studies provided important evidence for clinical research on TA1-IFN, and also brought new hope for hepatitis B therapy.

Antiviral Agents ; pharmacology ; Hepatitis B virus ; drug effects ; Humans ; Interferon-alpha ; biosynthesis ; genetics ; pharmacology ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; pharmacology ; Thymosin ; biosynthesis ; genetics ; pharmacology

The expression of major human apurinic/apyrimidinic DNA endonuclease (APEX) from its cDNA in E. coli (DH5 alpha) was attempted in order to obtain a biologically active recombinant APEX. E. coli cells were transformed by a prokaryotic translation vector (pGEX-4T-3) harboring APEX cDNA. GST-APEX fusion protein with a molecular weight of 6.3 KDa was induced by IPTG (1.0 mM) treatment. Western blot immunodetection identified the induced protein as the GST-APEX fusion protein. The survival rate of E. coli cells (DH5 alpha) transformed with pGEX-4T-3-APEX increased when the cells were treated with N-diethyl-N-nitrosamine (DENA) or 3'-methyl-4-monomethylaminoazobenzene (3'-MeMAB), indicating that APEX expression had a protective effect on the cytotoxicity of these carcinogens. The fusion protein extracted from E. coli cells and purified by GSH-agarose gel affinity chromatography exhibited APEX activity. Treatment of thrombin to the GST-APEX fusion protein and affinity purification followed by Sephacryl S-100 gel filtration resulted in APEX peptide with MW 36 KDa, which exhibited AP DNA repair activity (8,7000 EU/mg protein). N-ethylmaleimide (0.1 mM) or AMP (0.98 mM) inhibited APEX activity by 50% and kinetic analysis indicated that the recombinant APEX (rAPEX) had a Km value of 0.022 microM (AP sites for AP DNA) and the Ki value was 0.48 mM for AMP. These results indicated that E. coli cells expressing biologically active GST-APEX were resistant to the cell damage caused by chemical carcinogens and that rAPEX purified from E. coli cells transformed with APEX cDNA-inserted translation vector was similar to native APEX in some properties.
Carbon-Oxygen Lyases/biosynthesis* ; Diethylnitrosamine/pharmacology ; Escherichia coli/genetics ; Escherichia coli/drug effects ; Human ; Recombinant Fusion Proteins/biosynthesis*

The expression of cDNA encoding Tachyleus auti-lipoposaccharide (LPS) factor, which is of interest for use as a potential inhibitor of the common core subunit of Gram-negative bacterial endotoxin. First, the TALF gene was inserted into expression vectors pGEX-4T-2, pET22b and pET28a to construct recombinant expression plasmids. The recombinant plasmids were transformed to E. coli BL21 (DE3) and the expression of TALF was examined. Results show that TALF in pET22b and pET28a vectors can't be expressed. Only the fusion protein GST-TALF was expressed in E. coli BL21 existing as inclusion bodies. From 1 liter of culture, about 4mg of fusion protein GST-TALF with 91% purity was finally obtained. No apparent bactericidal activity and LPS neutralizing activity of the fusion protein GST-TALF were found. After digested with thrombin, the fusion protein GST-TALF exhibited strong bactericidal activity and LPS neutralizing activity.
Antimicrobial Cationic Peptides ; Arthropod Proteins ; Escherichia coli ; genetics ; Glutathione Transferase ; genetics ; Invertebrate Hormones ; genetics ; pharmacology ; Lipopolysaccharides ; antagonists & inhibitors ; Plasmids ; Recombinant Fusion Proteins ; biosynthesis ; pharmacology

In this study, we expressed and purified supercharged green fluorescent protein (+36GFP) that we used to study its combination with nucleic acid and its cell transduction efficiency as carrier of DNA. We transformed pET+36GFP-HA2 plasmid into Escherichia coli BL21 (DE3), then expressed and purified the target protein. We used the protein to transduce a variety of mammalian cell lines including B16 cells, 293 cells, A549 cells and HepG2 cells at specified protein concentrations. Transduction efficiency of the protein was analyzed by flow cytometry. Under laser scanning confocal microscope, we observed visually transduction efficiency of +36GFP protein (100 nmol/L) to A549 cells. We incubated +36GFP with plasmid DNA and analyzed their binding ability with gel mobility shift assay. Then we transduced cells with the mixture of plasmid DNA/+36GFP protein at various ratio and detected the expression of reporter gene by using laser scanning confocal microscope and flow cytometry. The experimental results demonstrate that +36GFP had high transduction efficiency, and as the concentration increased, the efficiency improved in a dose-dependent manner. Gel mobility shift assay indicates that +36GFP could bind to plasmid DNA, blocking the migration of DNA in the gel in a concentration-dependent manner. After the plasmid wrapped by +36GFP penetrated into cells, the cells could express target protein efficiently, proving that +36GFP had the ability to carry nucleic acids into cells. Sucussful expression and purification of +36GFP protein confirms its high efficiency of cell transduction and its ability as carrier to deliver exogenous nucleic acids into cells.
Cell Line, Tumor ; DNA ; genetics ; metabolism ; Escherichia coli ; genetics ; metabolism ; Green Fluorescent Proteins ; biosynthesis ; genetics ; pharmacology ; Humans ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; pharmacology ; Transduction, Genetic ; methods ; Transfection

OBJECTIVETo generate a recombinant expression system of repeated serial antibiotic peptide Alloferon-1 DNA segment with trypsin digestion site and to determine its anti-tumor activity in vitro.

METHODSA 14 repeated serial DNA segment of Alloferon-1 with a lysine residual at the C-end that acts as the trypsin digestion site was constructed. pET42a vector and E.coli BL21DE3 were applied to generate the prokaryotic expression system of the repeated serial DNA segment of Alloferon-1. The yield of target recombinant product was measured by SDS-PAGE and Bio-Rad Gel image system. Ni-NTA affinity column, trypsin digestion and Sephadex G-50 column were used to purify 14 rAlloferon-1-K fusion protein and rAlloferon-1-K monomer. By using the co-cultivation of BALB/c mouse splenocyte with K562, KB or SGC tumor cells and CCK-8 detection method, the effects of rAlloferon-1-K, chemosynthetic Alloferon-1 (cAlloferon-1) and Alloferon-1-K (cAlloferon-1-K) on the growth and proliferation of tumor cells were detected.

RESULTSThe prokaryotic expression system E.coli BL21DE3pET42a-14 Alloferon-1-K efficiently expressed 14 rAlloferon-1-K fusion protein under inducement of IPTG,and the yield of fusion protein was approximate 30% of the total bacterial proteins. 0.1≊10 ng/ml rAlloferon-1-K remarkably increased the effect of mouse splenocytes to inhibit the growth and proliferation of K562, KB and SGC cells (P<0.05), and there was no statistically significant difference of the anti-tumor ability of rAlloferon-1-K compared to that of cAlloferon-1 or cAlloferon-1-K (P>0.05).

CONCLUSIONA prokaryotic expression system of repeated serial Alloferon-1 DNA segment has been successfully constructed with high yield of rAlloferon-1-K, which maintains anti-tumor activity in vitro.

Animals ; Antineoplastic Agents ; pharmacology ; Cell Line, Tumor ; Genetic Vectors ; Humans ; Male ; Mice ; Mice, Inbred BALB C ; Peptides ; genetics ; pharmacology ; Recombinant Fusion Proteins ; biosynthesis ; genetics ; pharmacology