Total soluble proteins of different life stages, filamentous sporophytes cultivated in high temperatures, and blade gametophytes harvested in different seasons, were identified by SDS-PAGE. The types and amounts of ex...Total soluble proteins of different life stages, filamentous sporophytes cultivated in high temperatures, and blade gametophytes harvested in different seasons, were identified by SDS-PAGE. The types and amounts of expressed proteins also varied amongst the samples. The fewest soluble proteins were present in filamentous sporophytes. There were more types and amounts of soluble protein in conchospores than in filamentous sporophytes, but fewer than in bulgy sporophytes. More types of protein were detected in filamentous sporophytes cultivated in high temperatures than in those growing in normal situations. The most types and amounts of protein were found in blade gametophytes in all samples. Blade gametophytes harvested last year and stored at -20 ℃ showed only minor differences in expression of proteins when compared with those harvested in different seasons.展开更多
AIM:To develop a new method to produce recombinant reprogramming proteins,c Myc,Klf4,Oct4,and Sox2,in soluble format with low cost for the generation of induced pluripotent stem cells(i PSCs).METHODS:A short polyp...AIM:To develop a new method to produce recombinant reprogramming proteins,c Myc,Klf4,Oct4,and Sox2,in soluble format with low cost for the generation of induced pluripotent stem cells(i PSCs).METHODS:A short polypeptide sequence derived from the HIV trans-activator of transcription protein(TAT) and the nucleus localization signal(NLS) polypeptide were fused to the N terminus of the reprogramming proteins and they were constructed into p Cold-SUMO vector which can extremely improve the solubility of recombinant proteins.Then these vector plasmids were transformed into E.coli BL21(DE3) Chaperone competent cells for amplification.The solubility of these recombinant proteins was determined by SDS-PAGE and Coomassie brilliant blue staining.The recombinant proteins were purified by NiNTA resin and identified by Western blot.The transduction of these proteins into HEK 293 T cells were evaluated by immunofluorescence staining.RESULTS:These four reprogramming proteins could be produced in soluble format in p Cold-SUMO expression vector system with the assistance of chaperone proteins in bacteria.The proteins were purified successfully with a purity of over 70% with a relative high transduction rate into 293 cells.CONCLUSION:The results in the present study indicate the four important reprogramming proteins,c Myc,Klf4,Oct4,and Sox2,can be produced in soluble format in bacteria with low cost.Our new method thus might be expected to greatly contribute to the future study of i PSCs.展开更多
A 1440bp open-reading frame encoding D-hydantoinase from Pseudomonas putida YZ-26 was cloned and sequenced( GenBank AY387829). The DNA fragment was inserted into Nde and BamHI sites of vector pET-3a, yielding a reco...A 1440bp open-reading frame encoding D-hydantoinase from Pseudomonas putida YZ-26 was cloned and sequenced( GenBank AY387829). The DNA fragment was inserted into Nde and BamHI sites of vector pET-3a, yielding a recombinant plasmid, pET-HDT. After being transferred into the host strain, the artificial strain, pET-HDT/ E. coli BL21 can express the D-hydantoinase as the soluble form in the Lura-Bertani medium without addition of any inducers. The activity of the enzyme toward substrate DL-hydantoin can reach 3000-4000 IU per cells from one-liter bacterial culture incubated at 30 ℃ for 10-12 h. By the comparison of amino acid sequence homology, hydrophobic residues analysis and secondary structure prediction, it was found that D-hydantoinase reported herein is quite similar to that from Pseudomonas putdia CCRC12857, and alike to that from Pseudomonas putdia DSM84 or other bacteria. A rapid and efficient purification procedure of the enzyme was performed by a three-step procedure: ammonium sulfate fractionation, phenyl Sepharose hydrophobic interaction chromatography and Sephacryl S-200 gel filtration. The molecular mass of the monomeric enzyme is 52042 Da as determined by MALDI-TOF mass spectrometry.展开更多
Glutathione peroxidase(GPX) is a sclenoenzyme that protects the biomembrane and other cellular components against oxidative damage. The selenium-containing single chain Fv fragment of monoelonal antibody 2173 (Se s...Glutathione peroxidase(GPX) is a sclenoenzyme that protects the biomembrane and other cellular components against oxidative damage. The selenium-containing single chain Fv fragment of monoelonal antibody 2173 (Se scFv2F3) is a kind of GPX mimic and it has a wide clinical applications because of its high activity and low antigenicity. Se-seFv2F3 is generated by the chemical modification of the single chain Fv fragment of monoelonal antibody 2F3 ( scFv2F3 ), which can be expressed in E. coll. In this article, the effect of chemical chaperones, such as glycerol, glucose, and β-cyclodextrin added to the culture medium, on the expression of soluble scFv2F3 was investigated. The expression level was evaluated by the determination of soluble scFv2F3 contents in the whole cell lysates. The results suggest that both glycerol and β-cyclodextrin greatly increase the expression level of soluble scFv2F3, and β-cyclodextrin is found to be more effective compared with glycerol. Glucose has a slight effect on the expression level of soluble scFv2F3. This is the first example, wherein β-cyclodextrin has been used as a chemical chaperone during the cell culture to improve the expression level of recombinant proteins. In addition, chemical chaperones are found to decrease the toxic effect of IPTG on cells.展开更多
To find optimal conditions for expressing the soluble form of sFv-2F3 and to study the purification and property of its derivative Se-sFv-2F3,the preferred expression conditions were investigated by means of orthogona...To find optimal conditions for expressing the soluble form of sFv-2F3 and to study the purification and property of its derivative Se-sFv-2F3,the preferred expression conditions were investigated by means of orthogonal design. These culture conditions included incubation temperature,inducer concentration, induction time and cell concentration. The evaluation of expression was accomplished by the analysis of whole cell lysates and the yield of soluble sFv-2F3 was calculated according to the analysis of Profinder(FTI-500,Pharmacia). The purification procedure was carried out via a two-step purification procedure consisting of ion-exchange chromatography,followed by immobilized metal affinity chromatography(IMAC). The antioxidant efficacy of Se-sFv-2F3 was demonstrated by the determination of the content of the main product of lipid peroxidation,MDA,the viability of cells and the activity of LDH. We obtained the preferred culture conditions to grow the engineered bacteria and the procedure for preparing soluble sFv-2F3 and confirmed the antioxidant efficacy of Se-sFv-2F3.展开更多
[Objective] The paper was to develop genetic engineering vaccine that can express α exotoxin antigen protein efficiently without destroying its immunogenicity for preventing and controlling the diseases caused by Clo...[Objective] The paper was to develop genetic engineering vaccine that can express α exotoxin antigen protein efficiently without destroying its immunogenicity for preventing and controlling the diseases caused by Clostridium perfringens. [Method] Efficiently expressed soluble recombinant α protein was obtained from Escherichia coli expression system by optimizing codon,removing signal peptide,selecting sequences with better hydrophilicity and antigenicity,and optimizing expression conditions. [Result] Mice obtained higher serum antibody level when immunized by α protein,and the immune protection rates against type A,type B,type C and type D C. perfringens were 100%,90%,85% and 90%,respectively. The antibody titer of mice within 7-14 d after the third immunization reached the peak. [Conclusion]The α protein has good immunogenicity,and can be further used to develop genetic engineering subunit vaccines for preventing C. perfringens.展开更多
In order to regulate the apoptosis induced by Fas FasL system, a soluble isoform of mouse Fas was cloned from thymocytes of immature mice with the primers designed according to the full length Fas cDNA sequence in t...In order to regulate the apoptosis induced by Fas FasL system, a soluble isoform of mouse Fas was cloned from thymocytes of immature mice with the primers designed according to the full length Fas cDNA sequence in the GeneBank. It was directionally inserted into the intermedium vector pUC19. DNA sequencing proved that it was consistent with the expected sequence. Then it was subcloned into the eukaryotic expression vector pCA13, which was used to construct the recombinant vector pCA13 FasC. By lipofectamine (LF2000) mediated transfection, pCA13 FasC was transfected into the 293 cells. RT PCR and Western blot indicated that the murine soluble Fas C protein was expressed in the 293 cells. Apoptosis inducing test showed that the expression of this murine Fas C could block the Fas induced apoptosis, which confirmed the biological activity of the recombinant Fas C.展开更多
[ Objective] The paper was to get effective soluble N protein to establish indirect ELISA method for Peste des petits ruminants (PPR). [ Method] Soluble N protein with high expression was obtained from Escherichia c...[ Objective] The paper was to get effective soluble N protein to establish indirect ELISA method for Peste des petits ruminants (PPR). [ Method] Soluble N protein with high expression was obtained from Escherichia coli expression system through codon optimization and optimization of expression conditions, and indirect ELISA detection method based on N protein was further established. [ Result] The assay had no cross reaction with other sheep pathogens. The intra- and inter-batch variation coefficients were less than 9%, indicating the method had good repeatability. Furthermore, totally 480 clinical serum samples were detec- ted by the assay, and the agreement rate with commercial ELISA kit (IDVET) was 98.33%. [ Conclusion] The study laid a foundation for further development of mature PPRV antibody detection kits.展开更多
Objective:To construct a secretory eukaryotic expression vector of DSG2 fused with the Fc region of the human IgG,to validate its expression in 293T cells,and to purify the secretory protein with biological activity.M...Objective:To construct a secretory eukaryotic expression vector of DSG2 fused with the Fc region of the human IgG,to validate its expression in 293T cells,and to purify the secretory protein with biological activity.Methods:The DSG2 extracellular domain fragment gene(DSG2ex),was amplified by PCR,and was inserted into the eukaryotic expression plasmid pCMV3-IgG1 to construct the recombinant eukaryotic expression plasmid-pCMV3-DSG2ex-IgG1.The successfully constructed eukaryotic expression plasmid was transfected into 293T cells to express and secrete DSG2 extracellular domain protein.The targeted protein was purified from the cell culture supernatant by Protein A affinity chromatography and confirmed by Western Blotting and ELISA.Results:The pCMV3-DSG2ex-IgG1 eukaryotic expression plasmid was successfully constructed.The highest protein expression level was obtained with 293T cells after 96 h of transfection.The relative molecular mass of the purified product was between 100 and 130 kDa was estimated by SDS-PAGE,which was consistent with the expectation.The yield of the purified protein reached 0.8 mg/ml with a purity over 90%.The purified DSG2 extracellular domain protein with IgG1 tag was recognized by IgG monoclonal antibodies by Western blotting.Moreover,the ELISA results showed that the prepared DSG2 extracellular domain protein had significant binding activity to human type 55 adenovirus Fiber Knob protein(HAdV-55).Conclusion:A simple and efficient method for eukaryotic expression and purification of human soluble DSG2 extracellular domain protein was successfully established,and biologically active DSG2 extracellular domain protein was purified,which laid the foundation for the later study of its protein function and anti-adenovirus drugs.展开更多
The acetylcholinesterase 2(AChE2)cloned from Plutella xylostella was first successfully expressed in methylotrophic yeast Pichia pastoris GS115.One transformant with high-level expression of the recombinant AChE(rA...The acetylcholinesterase 2(AChE2)cloned from Plutella xylostella was first successfully expressed in methylotrophic yeast Pichia pastoris GS115.One transformant with high-level expression of the recombinant AChE(rAChE,23.2 U mL-1in supernatant)was selected by plating on increasing concentrations of antibiotic G418 and by using a simple and specific chromogenic reaction with indoxyl acetate as a substrate.The maximum production of r ACh E reached about 11.8 mg of the enzyme protein per liter of culture.The r ACh E was first precipitated with ammonium sulfate(50%saturation)and then purified with procainamide affinity column chromatography.The enzyme was purified 12.1-fold with a yield of 22.8%and a high specific activity of 448.3 U mg-1.It was sensitive to inhibition by methamidophos and pirimicarb,the calculated 50% inhibitory concentration(IC50)values of the two pesticides were 0.357 and 0.888 mg L-1,respectively,and the calculated 70% inhibitory concentration(IC70)values were 0.521 and 0.839 mg L-1,respectively.The results suggested that it has a potential application in the detection of pesticide residues.展开更多
Alpha-interferon 2b (IFN 2b) was produced both in soluble and insoluble forms from recombinant E. coli. The dissolution of the expressed IFN 2b in inclusion body was carried out and it was found that the optimal condi...Alpha-interferon 2b (IFN 2b) was produced both in soluble and insoluble forms from recombinant E. coli. The dissolution of the expressed IFN 2b in inclusion body was carried out and it was found that the optimal condition to dissolve the expressed protein was 7 mol稬1guanidinium salt solution at pH 3.0. The resultant solution was diluted 20 times using pH 6.0 buffer to refold the protein correctly. The cation exchange column was employed to purify both refolded and soluble IFN 2b. For soluble IFN sample, high IFN 2b recovery yield (92.1%) with 91.7% purity was obtained in the eluate. However, for refolded IFN sample, only 72.7% of IFN 2b was recovered with relatively low purity (56.8%) by cation exchange chromatography. Although the expression level of insoluble IFN was higher than that of co-expressed soluble IFN in this recombinant E. coli cells, the productivity of bioactive IFN 2b was higher with soluble expressed IFN after primary purification process. Soluble expression of foreign proteins in recombinant bacteria might be an alternative strategy for efficient production of heterogeneous pro-teins due to high bioactivity and simple downstream protein purification process.展开更多
Using genomic DNA of bolting-tolerant lettuce as a template,flanking fragments of lettuce plastid rpo A gene were amplified and cloned by PCR. Targeting the sites of these two fragments,homologous recombinant fragment...Using genomic DNA of bolting-tolerant lettuce as a template,flanking fragments of lettuce plastid rpo A gene were amplified and cloned by PCR. Targeting the sites of these two fragments,homologous recombinant fragments of exogenous gene were integrated to construct lettuce plastid expression vector p Brpo AGFP,which harbored the expression cassette Prrn-gfp-aad A-Tpsb A. The results showed that the amplified flanking fragments were 1.2 and 1.1 kb in size. After sequencing,restriction digestion,ligation and transformation,lettuce plastid expression vector containing expression cassette Prrn-gfp-aad A-Tpsb A was constructed and confirmed by SDS-PAGE electrophoresis. The results of SDS-PAGE electrophoresis indicated that gfp gene was efficiently expressed under the regulation of plasmid specific promoter Prrn and terminator Tpsb A. GFP accounted for 45. 6% of total soluble proteins; inclusion bodies accounted for 47.5 % of bacterial proteins,which reached relatively high expression levels. The construction of lettuce plastid expression vector p Brpo A-GFP laid a solid foundation for establishment of subsequent lettuce plastid transformation system and genetic improvement of lettuce using various functional genes.展开更多
A novel strategy to enhance the expression efficiency of cloned target gene in Escherichia coli was developed. The whole expression cartridge , consisting of promoter. SD sequence , target gene and transcription termi...A novel strategy to enhance the expression efficiency of cloned target gene in Escherichia coli was developed. The whole expression cartridge , consisting of promoter. SD sequence , target gene and transcription terminator, was tandem repeatedly engineered into a expression plasmid. Consequently, the copy number of specific gene was increased substantially, leading to the improvement of expression efficiency.Using this approach, a recombinant plasmid , designed as PLYD, was constructed and transformated into the Escherichia coli strain DH5α. Upon induction , the desired protein was synthesized in a considerable level and accumulated up to 63% of the total cell proteins. The present study revealed that tandem repeating of expression cartridge provided a convenient means to improve expression level efficiently.展开更多
Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors known to play a pivotal role in regulations of metabolism. In order to yield soluble ligand binding domain of PPARδ (P...Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors known to play a pivotal role in regulations of metabolism. In order to yield soluble ligand binding domain of PPARδ (PPARδLBD) for screening ligands, the cDNA was amplified using total RNA from HepG2 cells by RT-PCR. Then the enzyme-digested product was inserted . downstream of the malE gene in the vectorpMAL-p2x, which encoded maltose-binding protein (MBP), resulting in the expression of an MBP-PPARδLBD fusion protein. The recombinant plasmid was transformed into E. coli TBI that was cultured shakily at 30 ℃, 200 r/min and induced by 0.4 mmol/L IPTG for 6 h. The cells were harvested by centrifugation and broken by sonication. The expressed fusion protein was soluble and accounted for 0.31 of the total protein in the supernatant. Western blot analysis showed that the expressed MBP-PPARδLBD could bind to anti-MBP-antibody. The MBP-PPARδLBD fusion protein of 77 kDa and the PPARδLBD protein of 34 kDa were obtained by amylose-resin affinity chromatography without or with digestion of Factor Xa. They were both homogeneity, judged by SDS-PAGE. The recombinant MBP-PPARδLBD and PPARδLBD protein with high purity is obtained, which provides the necessary material for screening and researching PPARδ ligands.展开更多
The Rhodobacter capsulatus hemA gene, which encodes 5-aminolevulinic acid synthase (ALAS), was expressed in Escherichia coil Rosetta (DE3) and the enzymatic properties of the purified recombinant ALAS (RC-ALAS) ...The Rhodobacter capsulatus hemA gene, which encodes 5-aminolevulinic acid synthase (ALAS), was expressed in Escherichia coil Rosetta (DE3) and the enzymatic properties of the purified recombinant ALAS (RC-ALAS) were studied. Compared with ALASs encoded by hemA genes from Agrobacterium radiobacter(AR-ALAS) and Rhodobacter sphaeroides (RS-ALAS), the specific activity of RC-ALAS reached 198.2 U/mg, which was about 31.2% and 69.5% higher than those of AR-ALAS (151.1 U/mg) and RS-ALAS (116.9 U/mg), respectively. The optimum pH values and temperatures of the three above mentioned enzymes were all pH 7.5 and 37 ℃, respectively. Moreover, RC-ALAS was more sensitive to pH, while the other two were sensitive to temperature. The effects of metals, ethylene diamine tetraacetic acid (EDTA), and sodium dodecyl sulfate (SDS) on the three ALASs were also investigated. The results indicate that they had the same effects on the activities of the three ALASs. SDS and metal ions such as Co^2+, Zn^2+, and Cu^2+ strongly inhibited the activities of the ALASs, while Mn^2+ exerted slight inhibition, and K^+, Ca^2+, Ba^2+, Mg^2+, or EDTA had no significant effect. The specificity constant of succinyl coenzyme A [(kcatlKm)^S-CoA] of RC-ALAS was 1.4989, which was higher than those of AR-ALAS (0.7456) and RS-ALAS (1.1699), showing its high catalytic efficiency. The fed-batch fermentation was conducted using the recombinant strain containing the R. capsulatus hemA gene, and the yield of 5-aminolevulinic acid (ALA) achieved was 8.8 g/L (67 mmol/L) under the appropriate conditions.展开更多
A co-expressing system ofDsbA-DsbAmut was suggested for the first time to enhance the soluble expression of human trypsin-1. As a control, leaderless DsbA chaperone was also co-expressed with human trypsin-1. Vectors ...A co-expressing system ofDsbA-DsbAmut was suggested for the first time to enhance the soluble expression of human trypsin-1. As a control, leaderless DsbA chaperone was also co-expressed with human trypsin-1. Vectors pET39b-trypsin and pET28a-DsbA- DsbAn^ut-trypsin with the above two DsbA fusion tag were constructed. The strain with vector pET39b-trypsin expressed fusion protein DsbA-trypsin in form of inclusion bodies. While in E. coli BL21 (DE3) strain with vector pET28a-DsbA-DsbAmUt-trypsin, the soluble expression of trypsin fusion protein was achieved. Under the optimized expression conditions, the soluble fraction accounted for about 49.43% of total DsbA-DsbAmUt-trypsin proteins in crude supernatant. The purification yield was 4.15% by nickel chelating chromatography and 3.3 mg activated trypsin with a purity of 88.68% was obtained from 1 L LB broth. To detect the possible functions of DsbA series chaperons in trypsin fusion protein, we analyzed the primary three-dimensional structure of fusion proteins, mainly focusing on the compatibleness between trypsin and fusion chaperons. The results suggested that (1) besides the primary function in periplasm, leaderless DsbA or DsbAmut may also act as a signal sequences-like leader targeted to periplasm that partly relieved the pressure from fusion protein overexpression and inclusion body formation, and (2) as there was significant soluble expression of DsbA-DsbAmUt-trypsin compared with DsbA-trypsin, DsbArout may function as charge or hydrophobic balance in recombinant protein DsbA-DsbAmut- trypsin.展开更多
The plasmid pTLIL-2,which only directed a low-level expression of human interleukin 2(IL-2) cDNA in E.coli,was reconstructed:a series of deletions were made in 3'non-coding region of human IL-2 cDNA,and 7 recombin...The plasmid pTLIL-2,which only directed a low-level expression of human interleukin 2(IL-2) cDNA in E.coli,was reconstructed:a series of deletions were made in 3'non-coding region of human IL-2 cDNA,and 7 recombinant plasmids with different deletions were selected,on the other hand, a Tac promoter sequence from pDR540 was inserted to upstream of IL-2 cDNA in pTLIL-2 so that pTLIL-2DT,which contains double Tac promoters,was constructed.And then,E.coli JM103 was transformed with the above 8 recombinant plasmids respectively.The expression efficiency of IL-2 cDNA in E.cbli transformed with different plasmids was evaluated by means of SDS-PAGE and measuring 3H-TdR incorporation of IL-2-dependent activated T lymphocytes in the presence of bacterial extracts.Three engineering strains with high efficiency of IL-2 expression were selected,and all of these strains could produce recombinant IL-2(rIL-2)4 times more than E.coil JM103/pTLIL-2.展开更多
【目的】糖外排转运蛋白(sugars will eventually be exported transporters,SWEETs)在植物生长发育过程中发挥重要作用,解析SWEETs基因在枸杞果实发育过程中对糖积累作用,为进一步揭示SWEETs基因在枸杞果实发育过程中的作用提供参考。...【目的】糖外排转运蛋白(sugars will eventually be exported transporters,SWEETs)在植物生长发育过程中发挥重要作用,解析SWEETs基因在枸杞果实发育过程中对糖积累作用,为进一步揭示SWEETs基因在枸杞果实发育过程中的作用提供参考。【方法】用生物信息学方法对枸杞SWEET基因(LbaSWEETs)进行全基因组鉴定,并用已发表的转录数据分析LbaSWEETs在果实发育时期的基因表达情况。【结果】枸杞SWEET基因家族共有37个成员,随机分布于10条染色体上,分别编码152~621个氨基酸,蛋白质分子质量为16.87~69.97 kD,等电点为4.96~9.86。亚细胞定位预测位于叶绿体或质膜,大多数含有7个跨膜螺旋。系统进化分析发现,37个LbaSWEETs蛋白可分为4个亚群,每个亚群的基因结构和保守基序组成相似。启动子元件分析表明:Lba-SWEETs基因启动子富含大量激素响应、逆境胁迫和生长发育响应元件。转录组数据和qRT-PCR分析表明:LbaSWEET9和LbaSWEET29基因表达量随果实成熟呈现显著增加。相关性分析结果表明,LbaSWEET9和LbaSWEET29基因表达量与果糖含量呈显著正相关。【结论】LbaSWEET9和LbaSWEET29基因是果糖积累的关键基因。展开更多
基金supported by the National Natural Science Foundation of China (No. 40706050, 40706048 and 30700619)the National Science & Technology Pillar Program (No. 2006BAD01A13 and 2008BAC49B04)+2 种基金National special fund for transgenic project (No. 2009ZX08009-019B)Natural Science Foundation of Shandong Province (No. 2009ZRA02075)and Qingdao Municipal Science and Technology plan project (No. 09-2-5-8-hy)
文摘Total soluble proteins of different life stages, filamentous sporophytes cultivated in high temperatures, and blade gametophytes harvested in different seasons, were identified by SDS-PAGE. The types and amounts of expressed proteins also varied amongst the samples. The fewest soluble proteins were present in filamentous sporophytes. There were more types and amounts of soluble protein in conchospores than in filamentous sporophytes, but fewer than in bulgy sporophytes. More types of protein were detected in filamentous sporophytes cultivated in high temperatures than in those growing in normal situations. The most types and amounts of protein were found in blade gametophytes in all samples. Blade gametophytes harvested last year and stored at -20 ℃ showed only minor differences in expression of proteins when compared with those harvested in different seasons.
基金Supported by the Foundation of Heilongjiang Provincial Foundation for Youths Project(No.QC2011C119)
文摘AIM:To develop a new method to produce recombinant reprogramming proteins,c Myc,Klf4,Oct4,and Sox2,in soluble format with low cost for the generation of induced pluripotent stem cells(i PSCs).METHODS:A short polypeptide sequence derived from the HIV trans-activator of transcription protein(TAT) and the nucleus localization signal(NLS) polypeptide were fused to the N terminus of the reprogramming proteins and they were constructed into p Cold-SUMO vector which can extremely improve the solubility of recombinant proteins.Then these vector plasmids were transformed into E.coli BL21(DE3) Chaperone competent cells for amplification.The solubility of these recombinant proteins was determined by SDS-PAGE and Coomassie brilliant blue staining.The recombinant proteins were purified by NiNTA resin and identified by Western blot.The transduction of these proteins into HEK 293 T cells were evaluated by immunofluorescence staining.RESULTS:These four reprogramming proteins could be produced in soluble format in p Cold-SUMO expression vector system with the assistance of chaperone proteins in bacteria.The proteins were purified successfully with a purity of over 70% with a relative high transduction rate into 293 cells.CONCLUSION:The results in the present study indicate the four important reprogramming proteins,c Myc,Klf4,Oct4,and Sox2,can be produced in soluble format in bacteria with low cost.Our new method thus might be expected to greatly contribute to the future study of i PSCs.
基金Supported by the Natural Science Foundation of Shanxi Province(No.20031042).
文摘A 1440bp open-reading frame encoding D-hydantoinase from Pseudomonas putida YZ-26 was cloned and sequenced( GenBank AY387829). The DNA fragment was inserted into Nde and BamHI sites of vector pET-3a, yielding a recombinant plasmid, pET-HDT. After being transferred into the host strain, the artificial strain, pET-HDT/ E. coli BL21 can express the D-hydantoinase as the soluble form in the Lura-Bertani medium without addition of any inducers. The activity of the enzyme toward substrate DL-hydantoin can reach 3000-4000 IU per cells from one-liter bacterial culture incubated at 30 ℃ for 10-12 h. By the comparison of amino acid sequence homology, hydrophobic residues analysis and secondary structure prediction, it was found that D-hydantoinase reported herein is quite similar to that from Pseudomonas putdia CCRC12857, and alike to that from Pseudomonas putdia DSM84 or other bacteria. A rapid and efficient purification procedure of the enzyme was performed by a three-step procedure: ammonium sulfate fractionation, phenyl Sepharose hydrophobic interaction chromatography and Sephacryl S-200 gel filtration. The molecular mass of the monomeric enzyme is 52042 Da as determined by MALDI-TOF mass spectrometry.
基金Supported by the National Natural Science Foundation of China(Nos 20572035 and 30200050)
文摘Glutathione peroxidase(GPX) is a sclenoenzyme that protects the biomembrane and other cellular components against oxidative damage. The selenium-containing single chain Fv fragment of monoelonal antibody 2173 (Se scFv2F3) is a kind of GPX mimic and it has a wide clinical applications because of its high activity and low antigenicity. Se-seFv2F3 is generated by the chemical modification of the single chain Fv fragment of monoelonal antibody 2F3 ( scFv2F3 ), which can be expressed in E. coll. In this article, the effect of chemical chaperones, such as glycerol, glucose, and β-cyclodextrin added to the culture medium, on the expression of soluble scFv2F3 was investigated. The expression level was evaluated by the determination of soluble scFv2F3 contents in the whole cell lysates. The results suggest that both glycerol and β-cyclodextrin greatly increase the expression level of soluble scFv2F3, and β-cyclodextrin is found to be more effective compared with glycerol. Glucose has a slight effect on the expression level of soluble scFv2F3. This is the first example, wherein β-cyclodextrin has been used as a chemical chaperone during the cell culture to improve the expression level of recombinant proteins. In addition, chemical chaperones are found to decrease the toxic effect of IPTG on cells.
文摘To find optimal conditions for expressing the soluble form of sFv-2F3 and to study the purification and property of its derivative Se-sFv-2F3,the preferred expression conditions were investigated by means of orthogonal design. These culture conditions included incubation temperature,inducer concentration, induction time and cell concentration. The evaluation of expression was accomplished by the analysis of whole cell lysates and the yield of soluble sFv-2F3 was calculated according to the analysis of Profinder(FTI-500,Pharmacia). The purification procedure was carried out via a two-step purification procedure consisting of ion-exchange chromatography,followed by immobilized metal affinity chromatography(IMAC). The antioxidant efficacy of Se-sFv-2F3 was demonstrated by the determination of the content of the main product of lipid peroxidation,MDA,the viability of cells and the activity of LDH. We obtained the preferred culture conditions to grow the engineered bacteria and the procedure for preparing soluble sFv-2F3 and confirmed the antioxidant efficacy of Se-sFv-2F3.
基金Supported by the 13th Five-Year National Key Research and Development Program(2016YFD0500901)
文摘[Objective] The paper was to develop genetic engineering vaccine that can express α exotoxin antigen protein efficiently without destroying its immunogenicity for preventing and controlling the diseases caused by Clostridium perfringens. [Method] Efficiently expressed soluble recombinant α protein was obtained from Escherichia coli expression system by optimizing codon,removing signal peptide,selecting sequences with better hydrophilicity and antigenicity,and optimizing expression conditions. [Result] Mice obtained higher serum antibody level when immunized by α protein,and the immune protection rates against type A,type B,type C and type D C. perfringens were 100%,90%,85% and 90%,respectively. The antibody titer of mice within 7-14 d after the third immunization reached the peak. [Conclusion]The α protein has good immunogenicity,and can be further used to develop genetic engineering subunit vaccines for preventing C. perfringens.
基金a grant from the NationalNatural Science Fundation of China(Serial No.3 9970 70 8)
文摘In order to regulate the apoptosis induced by Fas FasL system, a soluble isoform of mouse Fas was cloned from thymocytes of immature mice with the primers designed according to the full length Fas cDNA sequence in the GeneBank. It was directionally inserted into the intermedium vector pUC19. DNA sequencing proved that it was consistent with the expected sequence. Then it was subcloned into the eukaryotic expression vector pCA13, which was used to construct the recombinant vector pCA13 FasC. By lipofectamine (LF2000) mediated transfection, pCA13 FasC was transfected into the 293 cells. RT PCR and Western blot indicated that the murine soluble Fas C protein was expressed in the 293 cells. Apoptosis inducing test showed that the expression of this murine Fas C could block the Fas induced apoptosis, which confirmed the biological activity of the recombinant Fas C.
基金Supported by New Diagnosis and Detection Technology Research for Major Animal Diseases in Cattle and Sheep(No.2016YFD0500901)
文摘[ Objective] The paper was to get effective soluble N protein to establish indirect ELISA method for Peste des petits ruminants (PPR). [ Method] Soluble N protein with high expression was obtained from Escherichia coli expression system through codon optimization and optimization of expression conditions, and indirect ELISA detection method based on N protein was further established. [ Result] The assay had no cross reaction with other sheep pathogens. The intra- and inter-batch variation coefficients were less than 9%, indicating the method had good repeatability. Furthermore, totally 480 clinical serum samples were detec- ted by the assay, and the agreement rate with commercial ELISA kit (IDVET) was 98.33%. [ Conclusion] The study laid a foundation for further development of mature PPRV antibody detection kits.
基金Nanjing Science and Technology Plan Project(No.ZX20200009)Jiangsu Province Postgraduate Research and Practice Innovation Program(No.SJCX22-0895)。
文摘Objective:To construct a secretory eukaryotic expression vector of DSG2 fused with the Fc region of the human IgG,to validate its expression in 293T cells,and to purify the secretory protein with biological activity.Methods:The DSG2 extracellular domain fragment gene(DSG2ex),was amplified by PCR,and was inserted into the eukaryotic expression plasmid pCMV3-IgG1 to construct the recombinant eukaryotic expression plasmid-pCMV3-DSG2ex-IgG1.The successfully constructed eukaryotic expression plasmid was transfected into 293T cells to express and secrete DSG2 extracellular domain protein.The targeted protein was purified from the cell culture supernatant by Protein A affinity chromatography and confirmed by Western Blotting and ELISA.Results:The pCMV3-DSG2ex-IgG1 eukaryotic expression plasmid was successfully constructed.The highest protein expression level was obtained with 293T cells after 96 h of transfection.The relative molecular mass of the purified product was between 100 and 130 kDa was estimated by SDS-PAGE,which was consistent with the expectation.The yield of the purified protein reached 0.8 mg/ml with a purity over 90%.The purified DSG2 extracellular domain protein with IgG1 tag was recognized by IgG monoclonal antibodies by Western blotting.Moreover,the ELISA results showed that the prepared DSG2 extracellular domain protein had significant binding activity to human type 55 adenovirus Fiber Knob protein(HAdV-55).Conclusion:A simple and efficient method for eukaryotic expression and purification of human soluble DSG2 extracellular domain protein was successfully established,and biologically active DSG2 extracellular domain protein was purified,which laid the foundation for the later study of its protein function and anti-adenovirus drugs.
基金supported by a grant from the Public Benefit Research Foundation of China (200903052)the Science and Technology Department of Guangdong Province, China (2009A020101003)
文摘The acetylcholinesterase 2(AChE2)cloned from Plutella xylostella was first successfully expressed in methylotrophic yeast Pichia pastoris GS115.One transformant with high-level expression of the recombinant AChE(rAChE,23.2 U mL-1in supernatant)was selected by plating on increasing concentrations of antibiotic G418 and by using a simple and specific chromogenic reaction with indoxyl acetate as a substrate.The maximum production of r ACh E reached about 11.8 mg of the enzyme protein per liter of culture.The r ACh E was first precipitated with ammonium sulfate(50%saturation)and then purified with procainamide affinity column chromatography.The enzyme was purified 12.1-fold with a yield of 22.8%and a high specific activity of 448.3 U mg-1.It was sensitive to inhibition by methamidophos and pirimicarb,the calculated 50% inhibitory concentration(IC50)values of the two pesticides were 0.357 and 0.888 mg L-1,respectively,and the calculated 70% inhibitory concentration(IC70)values were 0.521 and 0.839 mg L-1,respectively.The results suggested that it has a potential application in the detection of pesticide residues.
文摘Alpha-interferon 2b (IFN 2b) was produced both in soluble and insoluble forms from recombinant E. coli. The dissolution of the expressed IFN 2b in inclusion body was carried out and it was found that the optimal condition to dissolve the expressed protein was 7 mol稬1guanidinium salt solution at pH 3.0. The resultant solution was diluted 20 times using pH 6.0 buffer to refold the protein correctly. The cation exchange column was employed to purify both refolded and soluble IFN 2b. For soluble IFN sample, high IFN 2b recovery yield (92.1%) with 91.7% purity was obtained in the eluate. However, for refolded IFN sample, only 72.7% of IFN 2b was recovered with relatively low purity (56.8%) by cation exchange chromatography. Although the expression level of insoluble IFN was higher than that of co-expressed soluble IFN in this recombinant E. coli cells, the productivity of bioactive IFN 2b was higher with soluble expressed IFN after primary purification process. Soluble expression of foreign proteins in recombinant bacteria might be an alternative strategy for efficient production of heterogeneous pro-teins due to high bioactivity and simple downstream protein purification process.
基金Supported by Natural Science Foundation of Yunnan Province(2011FB049)National Natural Science Foundation of China(31260481,31460516)+2 种基金Fund of Yunnan Education Department(2013Y251)Fund of the Department of Life Science and Technology,Kunming University(GXKM201505)Talent Fund for PhD(YJL11015)
文摘Using genomic DNA of bolting-tolerant lettuce as a template,flanking fragments of lettuce plastid rpo A gene were amplified and cloned by PCR. Targeting the sites of these two fragments,homologous recombinant fragments of exogenous gene were integrated to construct lettuce plastid expression vector p Brpo AGFP,which harbored the expression cassette Prrn-gfp-aad A-Tpsb A. The results showed that the amplified flanking fragments were 1.2 and 1.1 kb in size. After sequencing,restriction digestion,ligation and transformation,lettuce plastid expression vector containing expression cassette Prrn-gfp-aad A-Tpsb A was constructed and confirmed by SDS-PAGE electrophoresis. The results of SDS-PAGE electrophoresis indicated that gfp gene was efficiently expressed under the regulation of plasmid specific promoter Prrn and terminator Tpsb A. GFP accounted for 45. 6% of total soluble proteins; inclusion bodies accounted for 47.5 % of bacterial proteins,which reached relatively high expression levels. The construction of lettuce plastid expression vector p Brpo A-GFP laid a solid foundation for establishment of subsequent lettuce plastid transformation system and genetic improvement of lettuce using various functional genes.
文摘A novel strategy to enhance the expression efficiency of cloned target gene in Escherichia coli was developed. The whole expression cartridge , consisting of promoter. SD sequence , target gene and transcription terminator, was tandem repeatedly engineered into a expression plasmid. Consequently, the copy number of specific gene was increased substantially, leading to the improvement of expression efficiency.Using this approach, a recombinant plasmid , designed as PLYD, was constructed and transformated into the Escherichia coli strain DH5α. Upon induction , the desired protein was synthesized in a considerable level and accumulated up to 63% of the total cell proteins. The present study revealed that tandem repeating of expression cartridge provided a convenient means to improve expression level efficiently.
基金Supported by the National Natural Science Foundation of China (30572353)
文摘Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors known to play a pivotal role in regulations of metabolism. In order to yield soluble ligand binding domain of PPARδ (PPARδLBD) for screening ligands, the cDNA was amplified using total RNA from HepG2 cells by RT-PCR. Then the enzyme-digested product was inserted . downstream of the malE gene in the vectorpMAL-p2x, which encoded maltose-binding protein (MBP), resulting in the expression of an MBP-PPARδLBD fusion protein. The recombinant plasmid was transformed into E. coli TBI that was cultured shakily at 30 ℃, 200 r/min and induced by 0.4 mmol/L IPTG for 6 h. The cells were harvested by centrifugation and broken by sonication. The expressed fusion protein was soluble and accounted for 0.31 of the total protein in the supernatant. Western blot analysis showed that the expressed MBP-PPARδLBD could bind to anti-MBP-antibody. The MBP-PPARδLBD fusion protein of 77 kDa and the PPARδLBD protein of 34 kDa were obtained by amylose-resin affinity chromatography without or with digestion of Factor Xa. They were both homogeneity, judged by SDS-PAGE. The recombinant MBP-PPARδLBD and PPARδLBD protein with high purity is obtained, which provides the necessary material for screening and researching PPARδ ligands.
基金Project supported by the National Natural Science Foundation of China (No.20306026)the National Basic Research Program (973) of China (No.2007CB707805)
文摘The Rhodobacter capsulatus hemA gene, which encodes 5-aminolevulinic acid synthase (ALAS), was expressed in Escherichia coil Rosetta (DE3) and the enzymatic properties of the purified recombinant ALAS (RC-ALAS) were studied. Compared with ALASs encoded by hemA genes from Agrobacterium radiobacter(AR-ALAS) and Rhodobacter sphaeroides (RS-ALAS), the specific activity of RC-ALAS reached 198.2 U/mg, which was about 31.2% and 69.5% higher than those of AR-ALAS (151.1 U/mg) and RS-ALAS (116.9 U/mg), respectively. The optimum pH values and temperatures of the three above mentioned enzymes were all pH 7.5 and 37 ℃, respectively. Moreover, RC-ALAS was more sensitive to pH, while the other two were sensitive to temperature. The effects of metals, ethylene diamine tetraacetic acid (EDTA), and sodium dodecyl sulfate (SDS) on the three ALASs were also investigated. The results indicate that they had the same effects on the activities of the three ALASs. SDS and metal ions such as Co^2+, Zn^2+, and Cu^2+ strongly inhibited the activities of the ALASs, while Mn^2+ exerted slight inhibition, and K^+, Ca^2+, Ba^2+, Mg^2+, or EDTA had no significant effect. The specificity constant of succinyl coenzyme A [(kcatlKm)^S-CoA] of RC-ALAS was 1.4989, which was higher than those of AR-ALAS (0.7456) and RS-ALAS (1.1699), showing its high catalytic efficiency. The fed-batch fermentation was conducted using the recombinant strain containing the R. capsulatus hemA gene, and the yield of 5-aminolevulinic acid (ALA) achieved was 8.8 g/L (67 mmol/L) under the appropriate conditions.
基金Acknowledgements The present work was partially supported by the National Natural Science Foundation of China (Grant No. 31470967) and National Science and Technology Major Projects of China (Grant Nos. 2011ZX09201-301-05 and 2014ZX09508006-002-002).
文摘A co-expressing system ofDsbA-DsbAmut was suggested for the first time to enhance the soluble expression of human trypsin-1. As a control, leaderless DsbA chaperone was also co-expressed with human trypsin-1. Vectors pET39b-trypsin and pET28a-DsbA- DsbAn^ut-trypsin with the above two DsbA fusion tag were constructed. The strain with vector pET39b-trypsin expressed fusion protein DsbA-trypsin in form of inclusion bodies. While in E. coli BL21 (DE3) strain with vector pET28a-DsbA-DsbAmUt-trypsin, the soluble expression of trypsin fusion protein was achieved. Under the optimized expression conditions, the soluble fraction accounted for about 49.43% of total DsbA-DsbAmUt-trypsin proteins in crude supernatant. The purification yield was 4.15% by nickel chelating chromatography and 3.3 mg activated trypsin with a purity of 88.68% was obtained from 1 L LB broth. To detect the possible functions of DsbA series chaperons in trypsin fusion protein, we analyzed the primary three-dimensional structure of fusion proteins, mainly focusing on the compatibleness between trypsin and fusion chaperons. The results suggested that (1) besides the primary function in periplasm, leaderless DsbA or DsbAmut may also act as a signal sequences-like leader targeted to periplasm that partly relieved the pressure from fusion protein overexpression and inclusion body formation, and (2) as there was significant soluble expression of DsbA-DsbAmUt-trypsin compared with DsbA-trypsin, DsbArout may function as charge or hydrophobic balance in recombinant protein DsbA-DsbAmut- trypsin.
文摘The plasmid pTLIL-2,which only directed a low-level expression of human interleukin 2(IL-2) cDNA in E.coli,was reconstructed:a series of deletions were made in 3'non-coding region of human IL-2 cDNA,and 7 recombinant plasmids with different deletions were selected,on the other hand, a Tac promoter sequence from pDR540 was inserted to upstream of IL-2 cDNA in pTLIL-2 so that pTLIL-2DT,which contains double Tac promoters,was constructed.And then,E.coli JM103 was transformed with the above 8 recombinant plasmids respectively.The expression efficiency of IL-2 cDNA in E.cbli transformed with different plasmids was evaluated by means of SDS-PAGE and measuring 3H-TdR incorporation of IL-2-dependent activated T lymphocytes in the presence of bacterial extracts.Three engineering strains with high efficiency of IL-2 expression were selected,and all of these strains could produce recombinant IL-2(rIL-2)4 times more than E.coil JM103/pTLIL-2.
文摘【目的】糖外排转运蛋白(sugars will eventually be exported transporters,SWEETs)在植物生长发育过程中发挥重要作用,解析SWEETs基因在枸杞果实发育过程中对糖积累作用,为进一步揭示SWEETs基因在枸杞果实发育过程中的作用提供参考。【方法】用生物信息学方法对枸杞SWEET基因(LbaSWEETs)进行全基因组鉴定,并用已发表的转录数据分析LbaSWEETs在果实发育时期的基因表达情况。【结果】枸杞SWEET基因家族共有37个成员,随机分布于10条染色体上,分别编码152~621个氨基酸,蛋白质分子质量为16.87~69.97 kD,等电点为4.96~9.86。亚细胞定位预测位于叶绿体或质膜,大多数含有7个跨膜螺旋。系统进化分析发现,37个LbaSWEETs蛋白可分为4个亚群,每个亚群的基因结构和保守基序组成相似。启动子元件分析表明:Lba-SWEETs基因启动子富含大量激素响应、逆境胁迫和生长发育响应元件。转录组数据和qRT-PCR分析表明:LbaSWEET9和LbaSWEET29基因表达量随果实成熟呈现显著增加。相关性分析结果表明,LbaSWEET9和LbaSWEET29基因表达量与果糖含量呈显著正相关。【结论】LbaSWEET9和LbaSWEET29基因是果糖积累的关键基因。