In order to enhance the glutathione peroxidase（GPX） catalytic activity of the selenium-containing single-chain variable fragments（Se-scFv）, a novel human scFv was designed on the basis of the structure of human an...In order to enhance the glutathione peroxidase（GPX） catalytic activity of the selenium-containing single-chain variable fragments（Se-scFv）, a novel human scFv was designed on the basis of the structure of human antibody and optimized via bioinformatics methods such as homologous sequence analysis, three-dimensional（3D） model building, binding-site analysis and docking. The DNA sequence of the new human scFv was synthesized and cloned into the expression vector pET22b（＋）, then the scFv protein was expressed in soluble form in Escherichia coli BL21（DE3） and purified by Ni2＋-immobilized metal affinity chromatography（IMAC）. The serine residue of scFv in the active site was converted into selenocysteine（Sec） with the chemical modification method, thus, the human Se-scFv with GPX activity was obtained. The GPX activity of the Se-scFv protein was characterized. Compared with other Se-scFv, the new human Se-scFv showed similar efficiency for catalyzing the reduction of hydrogen peroxide by glutathione. It exhibited pH and temperature dependent catalytic activity and a typical ping-pong kinetic mechanism.展开更多
Total RNA was isolated from the hybridoma cell line （LC- 1 ）, which secretes anti-lung adenocarcinoma monoclonal antibody, and was transferred into cDNA. Based on the FRl （framework region l） and FR4 conserved reg...Total RNA was isolated from the hybridoma cell line （LC- 1 ）, which secretes anti-lung adenocarcinoma monoclonal antibody, and was transferred into cDNA. Based on the FRl （framework region l） and FR4 conserved regions of LC-1 gene, the variable regions of heavy chain （Vh） and light chain （Vl） were amplified, and the Vh and modified Vl were connected to single chain Fv （ScFv） by SOE-PCR （splice overlap extension PCR）. The modified ScFv was fused with green fluorescent protein （GFP） and introduced into E. coli JM109. The fusion protein induced by lPTG （Isopropylthiogalactoside） was about 57000 on a 10% SDS-PAGE gel （10% Sds Polyacrylamide Gel Electrophoresis）, and primarily manifested as inclusion bodies. The renatured protein purified by Ni-NTA Superflow resins showed ability to bind to antigen on SPC-A-l lung adenocarcinoma. In addition, the induced host cells fluoresced bright green under 395 nm wavelength, which indicated that the expected protein with dual activity was expressed in the prokaryotic system. The ScFv with GFP tag used in this research can be applied as a new reagent to detect immunological dye, and provide a feasible way to detect adenocarcinoma in a clinical setting.展开更多
Objective: To Obtain purified genetic eogineering recombinant scFv-fusion protein with potentialities of clinical application. Methods: Mouse anti-hepatocellular carcinoma (HCC) single chain Fv fragment (mscFv25 ) was...Objective: To Obtain purified genetic eogineering recombinant scFv-fusion protein with potentialities of clinical application. Methods: Mouse anti-hepatocellular carcinoma (HCC) single chain Fv fragment (mscFv25 ) was fused to human TNFa gene, then mscFv25-TNFa was subcloned into prokaryotic GST fusion expression vector pGEX 4T-l, and ex-. pressed in the host E. colt induced by IPTG. Expressed proteins as inclusion bodies were solubilized, solubilized and purified by GST affinity chromatography. The cytotoxity of mscFv25-TNFa was evaluated on SMMC-7721 by MTT, and the targeting therapeutic value was revealed in nude mice bearing HCC xenografts. Results: The specificity and affinity of mscFv25-TNFa were not markedly reduced compared with its parental antibody HAb25 against SMMC-7721 antigen. In vitro target cell SMMC-7721 was insensitive to mscFv25-TNFa. In the mscFv25-TNFa had certain targeting cytotoxicity and caused complete tumor disappearance in 4 of 14 mice, and the side effects of TNFa were much weaker in mscFv25-TNFa group than in group. Conclusion: SMMC-7721 may belong to the TNF-resistant type. While in the trial, mscFv25-TNFa caused complete tumor disappearance in 4 of 14 mice, but no disappearance in TNFa group, suggesting that mscFv25-TNFa had certain tar geting cytotoxicity, and the cytotoxicity of TNFa depended on some other factors in the. It may damage vascular endothelial cell and lead to ischemic necrosis, or induce the tumor cell to apoptosis and some agents to play the the of actinmycin-D in vivo. The targeting of mscFv25 can diminish unspecific cytotoxicity of TNFa, thus attenuate the side effects of TNFa.展开更多
Objective To obtain the gene of murine Single chain Fv fragment (ScFv) against human cervical cancer and to express it in E.coli . Methods The variable region gene fragments of the heavy and light chains, which were a...Objective To obtain the gene of murine Single chain Fv fragment (ScFv) against human cervical cancer and to express it in E.coli . Methods The variable region gene fragments of the heavy and light chains, which were amplified respectively using recombinant DNA techniques from CsA125 hybridoma cells, were spliced together through a flexible linker to ScFv against human cervical cancer. The ScFv genes were then cloned into expression vector pCANTAB 5E and expressed in E.coli HB2151 and TG1 respectively. The soluble ScFv were characterized by SDS-PAGE and Western blot. The antigen-binding activities of the soluble and phage displayed ScFv were assayed by ELISA and cell immunohistochemical analysis. Results The expressed ScFv antibodies were soluble and phage displayed. The soluble ScFv secreted and expressed in E.coli HB2151 induced by IPTG were confirmed with SDS-PAGE, Western blot and ELISA. The specific binding capacity of the soluble and phage displayed ScFv to the surface associated antigen of human cervical cancer cell line was further confirmed with immunohistochemical studies. Conclusion The soluble and phage displayed ScFv expressed in E.coli against human cervical cancer showed high, specific affinity for the cervical cancer cell line surface associated antigen.展开更多
The single chain variable fragments of antibodies(scFvs) against cTnI were screened from the phage display antibody library by using cTnI as the target antigen. After four rounds of panning, four clones(H2, G5, A9, B9...The single chain variable fragments of antibodies(scFvs) against cTnI were screened from the phage display antibody library by using cTnI as the target antigen. After four rounds of panning, four clones(H2, G5, A9, B9) from the phage display antibody library were verified to show higher binding affinity for cTnI by ELISA and to contain the variable region genes of the light and heavy chains of scFvs by sequencing. The variable region genes of scFvs H2 and G5 were successfully amplified by polymerase chain reactions(PCR) and cloned into expression vector pPELB and expressed as a soluble protein in E.coli Rosetta, whose expression yield was about 2% of total proteins. The expressed proteins were purified by nickel(Ni) affinity chromatography and a single band is shown in the position of 28 kDa on SDS-PAGE. The western blot analysis result verifies that the expressed scFv proteins are capable of binding with monoclonal antibodies against hexa-histidine, indicating that they are hexa-histidin-tagged aim proteins. The immunoassay demonstrates that the expressed scFv proteins are able to specifically react with cTnI molecules. The association constant(K_A) values range from 1.2×10 4 to 1.7 ×10 5 L/mol that are correspondent to the affinities of polyclonal antibodies against cTnI from rabbits. These antibodies can be valuable reagents for the immunoassay of cTnI.展开更多
基金Supported by the National Natural Science Foundation of China(No.30970608)the Applicative Technological Project of Bureau of Science and Technology of Changchun City, China(No.2009045)+1 种基金the Development and Planning Major Program of Jilin Provincial Science and Technology Department, China(No.20100948)the Innovation Method Fund of China (No.2008IM040800)
文摘In order to enhance the glutathione peroxidase（GPX） catalytic activity of the selenium-containing single-chain variable fragments（Se-scFv）, a novel human scFv was designed on the basis of the structure of human antibody and optimized via bioinformatics methods such as homologous sequence analysis, three-dimensional（3D） model building, binding-site analysis and docking. The DNA sequence of the new human scFv was synthesized and cloned into the expression vector pET22b（＋）, then the scFv protein was expressed in soluble form in Escherichia coli BL21（DE3） and purified by Ni2＋-immobilized metal affinity chromatography（IMAC）. The serine residue of scFv in the active site was converted into selenocysteine（Sec） with the chemical modification method, thus, the human Se-scFv with GPX activity was obtained. The GPX activity of the Se-scFv protein was characterized. Compared with other Se-scFv, the new human Se-scFv showed similar efficiency for catalyzing the reduction of hydrogen peroxide by glutathione. It exhibited pH and temperature dependent catalytic activity and a typical ping-pong kinetic mechanism.
基金Project (No. 396007) supported by the National Natural ScienceFoundation of China
文摘Total RNA was isolated from the hybridoma cell line （LC- 1 ）, which secretes anti-lung adenocarcinoma monoclonal antibody, and was transferred into cDNA. Based on the FRl （framework region l） and FR4 conserved regions of LC-1 gene, the variable regions of heavy chain （Vh） and light chain （Vl） were amplified, and the Vh and modified Vl were connected to single chain Fv （ScFv） by SOE-PCR （splice overlap extension PCR）. The modified ScFv was fused with green fluorescent protein （GFP） and introduced into E. coli JM109. The fusion protein induced by lPTG （Isopropylthiogalactoside） was about 57000 on a 10% SDS-PAGE gel （10% Sds Polyacrylamide Gel Electrophoresis）, and primarily manifested as inclusion bodies. The renatured protein purified by Ni-NTA Superflow resins showed ability to bind to antigen on SPC-A-l lung adenocarcinoma. In addition, the induced host cells fluoresced bright green under 395 nm wavelength, which indicated that the expected protein with dual activity was expressed in the prokaryotic system. The ScFv with GFP tag used in this research can be applied as a new reagent to detect immunological dye, and provide a feasible way to detect adenocarcinoma in a clinical setting.
文摘Objective: To Obtain purified genetic eogineering recombinant scFv-fusion protein with potentialities of clinical application. Methods: Mouse anti-hepatocellular carcinoma (HCC) single chain Fv fragment (mscFv25 ) was fused to human TNFa gene, then mscFv25-TNFa was subcloned into prokaryotic GST fusion expression vector pGEX 4T-l, and ex-. pressed in the host E. colt induced by IPTG. Expressed proteins as inclusion bodies were solubilized, solubilized and purified by GST affinity chromatography. The cytotoxity of mscFv25-TNFa was evaluated on SMMC-7721 by MTT, and the targeting therapeutic value was revealed in nude mice bearing HCC xenografts. Results: The specificity and affinity of mscFv25-TNFa were not markedly reduced compared with its parental antibody HAb25 against SMMC-7721 antigen. In vitro target cell SMMC-7721 was insensitive to mscFv25-TNFa. In the mscFv25-TNFa had certain targeting cytotoxicity and caused complete tumor disappearance in 4 of 14 mice, and the side effects of TNFa were much weaker in mscFv25-TNFa group than in group. Conclusion: SMMC-7721 may belong to the TNF-resistant type. While in the trial, mscFv25-TNFa caused complete tumor disappearance in 4 of 14 mice, but no disappearance in TNFa group, suggesting that mscFv25-TNFa had certain tar geting cytotoxicity, and the cytotoxicity of TNFa depended on some other factors in the. It may damage vascular endothelial cell and lead to ischemic necrosis, or induce the tumor cell to apoptosis and some agents to play the the of actinmycin-D in vivo. The targeting of mscFv25 can diminish unspecific cytotoxicity of TNFa, thus attenuate the side effects of TNFa.
文摘Objective To obtain the gene of murine Single chain Fv fragment (ScFv) against human cervical cancer and to express it in E.coli . Methods The variable region gene fragments of the heavy and light chains, which were amplified respectively using recombinant DNA techniques from CsA125 hybridoma cells, were spliced together through a flexible linker to ScFv against human cervical cancer. The ScFv genes were then cloned into expression vector pCANTAB 5E and expressed in E.coli HB2151 and TG1 respectively. The soluble ScFv were characterized by SDS-PAGE and Western blot. The antigen-binding activities of the soluble and phage displayed ScFv were assayed by ELISA and cell immunohistochemical analysis. Results The expressed ScFv antibodies were soluble and phage displayed. The soluble ScFv secreted and expressed in E.coli HB2151 induced by IPTG were confirmed with SDS-PAGE, Western blot and ELISA. The specific binding capacity of the soluble and phage displayed ScFv to the surface associated antigen of human cervical cancer cell line was further confirmed with immunohistochemical studies. Conclusion The soluble and phage displayed ScFv expressed in E.coli against human cervical cancer showed high, specific affinity for the cervical cancer cell line surface associated antigen.
文摘The single chain variable fragments of antibodies(scFvs) against cTnI were screened from the phage display antibody library by using cTnI as the target antigen. After four rounds of panning, four clones(H2, G5, A9, B9) from the phage display antibody library were verified to show higher binding affinity for cTnI by ELISA and to contain the variable region genes of the light and heavy chains of scFvs by sequencing. The variable region genes of scFvs H2 and G5 were successfully amplified by polymerase chain reactions(PCR) and cloned into expression vector pPELB and expressed as a soluble protein in E.coli Rosetta, whose expression yield was about 2% of total proteins. The expressed proteins were purified by nickel(Ni) affinity chromatography and a single band is shown in the position of 28 kDa on SDS-PAGE. The western blot analysis result verifies that the expressed scFv proteins are capable of binding with monoclonal antibodies against hexa-histidine, indicating that they are hexa-histidin-tagged aim proteins. The immunoassay demonstrates that the expressed scFv proteins are able to specifically react with cTnI molecules. The association constant(K_A) values range from 1.2×10 4 to 1.7 ×10 5 L/mol that are correspondent to the affinities of polyclonal antibodies against cTnI from rabbits. These antibodies can be valuable reagents for the immunoassay of cTnI.
