ABSTRACT
@#In order to study the effect of human deoxyribonuclease I(DNase I)on neutrophil extracellular traps(NETs)degradation, genetic engineering bacteria E. coli Rosetta(DE3)/pET32a-His-DNase I was constructed. The fusion protein His-DNase I was induced by lactose, and purified by Ni-affinity chromatography. Mouse neutrophils were extracted and stimulated with phorbol-12-myristate-13-acetate(PMA)to form NETs. The degradation activity of the fusion protein on NETs was detected by SytoxGreen and fluorescence microscopy. The results showed that the purified His-DNase I had high nuclease activity. This study provided the research foundation for further exploration of the clinical application of DNase I.
ABSTRACT
In order to study the relationship between Staphylococcal nuclease(SNase) and diabetes mellitus,genetic engineering bacteria E.coli BL21/pET28a-His-SNase was constructed,the expression of soluble extracellular protein SNase was induced and the a preliminary research was made on it.An expression vector pET28a-His-SNase plasmid containing the His-SNase gene was constructed and transformed into E.coli BL21 (DE3) competent cells.The protein was induced by lactose and purified by ultrasound destruction and Ni-affinity chromatography,respectively.It was then analyzed by SDS-PAGE and Western blot.The enzymatic properties for SNase has been preliminary studied as well.Results indicated that the purity of the correctly expressed fusion protein HisSNase was over 85％.SNase showed good activity within a wide range of pH and good heat resistance.This experiment might be a foundation work for the further study on the relationship between SNase and with diabetes.
ABSTRACT
Objective To identify the expression of sphingosine-1-phosphate receptor (S1PR) subtypes, C-myc and His tag proteins of human umbilical vein endothelial fusion cell line, EA.hy926 and human umbilical vein endothelial cells (HUVEC), CRL-1730 for studying the function of apolipoprotein M (ApoM)-S1P axis. Methods Two kinds of cells (EA. hy926 and CRL-1730) were cultured to reach the density of 60%-70% in vitro. Immunofluorescence technique was em?ployed to investigate the expressions of coagulation factorⅧ(FⅧ), ApoM, S1PR1-S1PR5, C-myc and His tag proteins. Re?sults (1) Two kinds of cells both expressed FⅧand ApoM. FⅧpresented scattered particle distribution in CRL-1730, while uniform distribution in EA.hy926. However, ApoM was strongly expressed and widely distributed in cytoplasm of two kinds of cells. (2) S1PR1-3 can be detected on their membrane other than S1PR4 and S1PR5. S1PR1 was highly expressed but S1PR2 and S1PR3 were in a low level expression. (3) Two kinds of cells both expressed C-myc and His tag proteins in cytoplasm. Conclusion Two kinds of cells have the properties of endothelial cells and can express FⅧ, ApoM, C-myc and His tag proteins. It is not suitable for choosing C-myc and/or His tag–conjugated recombinant ApoM to study the fuction of ApoM-S1P axis with these two kinds of cells.
ABSTRACT
The spike (S) and nucleocapsid (N) proteins, which are responsible for viral binding to cell surface receptors and the formation of ribonucleoprotein complexes during virion assembling, are major structure proteins of severe acute respiratory syndrome coronavirus (SARS-CoV). The expression of recombinant protein may give more accurate result for detecting SARS-CoV infection. A novel fusion protein,comprising of two fragments of N and S proteins from SARS-CoV, was prepared. Our computer-assisted analysis suggested that the immunodominant domains were located in the amino acid residues 1-227 of N protein and 450-650 of S protein, further the fusion of the two fragments did not change the immunochemical characteristics. The complementary DNA(cDNA) encoding N1-227 fused with S450-650 was obtained by sequence overlapping extension (SOE), and named NLS. It was cloned into pET-28a ( + ), an expression vector for His-tag fusion protein. This new constructed fusion protein was prokaryotic expressed in E. coli,and purified by metal chelate affinity chromatography with the purity over 95 %. The purified fusion protein was identified by anti-His monoclonal antibody and convalescence SARS patients serum. The NLS protein based ELISA showed that NLS maintained appropriate antigenicity and specificity to react with the sera of convalescent SARS patients. The functional NLS protein were successfully expressed and purified. And the fusion protein based ELISA can be used for detection of antibodies (Abs) against the S and N proteins of SARS-CoV. It may provided a novel diagnostic tool and have the potential application in developing of anti-SARS vaccine.
ABSTRACT
Objective:To investigate whether His-tag to change the immunogenicity of recombinant protein G1F/M2 of respiratory syncytial virus.Methods:The G1 and F/M2 gene fragments were amplified by PCR method and then ligated into the expressing vector pET-His or pET-DsbA-His.Each recombinant plasmid was transferred into E.coli BL21(DE3) and the expression was induced by IPTG.The expressed His-G1F/M2 or DsbA-His-G1F/M2 was purified by affinity chromatography.The latter was digested with thrombase and G1F/M2 was purified by affinity chromatography.His-G1F/M2 or G1F/M2 was used to immunize BALB/c mice.Anti-RSV antibody was measured by ELISA and RSV-specific CTL responses by MTT.Results:No significant difference was observed between the level of anti-RSV antibody or RSV-specific CTL response induced by G1F/M2 and that by His-G1F/M2.Conclusion:His-tag does not change the immunogenicity of recombinant protein G1F/M2 of respiratory syncytial virus.