Ferritin is considered as an ideal delivery system due to its precise targeting, reversible self-assembly, high biocompatibility, and easy modification. this study aims to express, purify, and identify three fusion ferritin proteins, and explore their tumor targeting. Three fusion ferritin genes were synthesized and cloned into prokaryotic expression vectors, and the recombinant proteins were purified by affinity chromatography with nickel columns. The fusion ferritin proteins were identified by native polyacrylamide gel electrophoresis (native-PAGE), Western blotting, and circular dichroism. Fluorescein 5-isothiocyanate (FITC) was used to react with fusion ferritin, and confocal laser scanning microscopy was employed to evaluate the tumor targeting of fusion ferritin. The reaction system of sulfo-cyanine7 (Cy7-SE) with fusion ferritin was injected into the tail vein of melanoma mice for in vivo tumor imaging to explore the tumor targeting of fusion ferritin. The results showed that soluble fusion ferritin proteins of about 21 kDa were expressed under the induction by isopropylthio-β-d-galactoside (IPTG), and the recombinant proteins with high purity were obtained. Western blotting showed that the recombinant proteins could be recognized by the corresponding antibodies. The target proteins were identified as multimers with α helixes by native-PAGE and circular dichroism. In vitro and in vivo tumor uptake experiments demonstrated that fusion ferritin was taken up by tumor cells and tumor tissue. This study successfully expressed, purified, and identified fusion ferritin, and verified its tumor uptake in vitro and in vivo, which laid a foundation for the application of ferritin in biomedicine.
Animals ; Mice ; Recombinant Fusion Proteins/isolation & purification* ; Ferritins/metabolism* ; Escherichia coli/metabolism* ; Melanoma, Experimental/metabolism* ; Humans

Carbamate pesticides, a new type of broad-spectrum pesticides for controlling pests, mites, and weeds, are developed to address the shortcomings of organochlorine and organophosphorus pesticides. Their widespread use and slow degradation have led to environmental pollution, causing damage to ecosystems and human health. Managing pesticide residues is a pressing issue in the current environmental protection. This study aims to investigate the expression of SyEst870, a member of the SGNH/GDSL hydrolase family in Sphingobium yanoikuyae, in a prokaryotic system and evaluate the ability of the recombinant protein to degrade carbamate pesticides. The prokaryotic expression vector pET-32a-SyEst870 was constructed and transformed into the Escherichia coli BL21 for heterologous expression. The purified protein was studied in terms of enzyme activity and effects of temperature, pH, and metal ions on the enzyme activity, with p-nitrophenol acetate as the substrate and based on the standard curve of p-nitrophenol. LC-MS (liquid chromatography-mass spectrometry) was employed to examine the degradation effects of SyEst870 on carbaryl, metolcarb, and isoprocarb. GC-MS (gas chromatography-mass spectrometry) was employed to detect the degradation products of SyEst870 for the three pesticides. The soluble protein SyEst870 was successfully obtained through the heterologous expression in Escherichia coli, which yielded an enzyme with the activity of 677.5 U after affinity chromatography. SyEst870 exhibited degradation rates of 82.34%, 84.43%, and 92.87% for carbaryl, metolcarb, and isoprocarb, respectively, at an initial concentration of 100 mg/L within 24 h at 30 ℃ and pH 7.0. The primary degradation products of carbaryl were identified as α-naphthol and methyl isocyanate. Metolcarb was mainly degraded into m-cresol and methyl isocyanate, and isoprocarb was mainly degraded into 2-isopropylphenol and methyl isocyanate. Compared with the half-life of carbamate pesticides in the natural environment, which ranges from a few days to several weeks, the recombinant protein SyEst870 can rapidly eliminate the residues of carbamate pesticides. This study lays a foundation for addressing pesticide residues in the environment and in fruits and vegetables.
Escherichia coli/metabolism* ; Sphingomonadaceae/genetics* ; Recombinant Proteins/metabolism* ; Biodegradation, Environmental ; Esterases/metabolism* ; Pesticides/isolation & purification* ; Carbamates/isolation & purification*

This study aims to establish an antibody detection method for porcine deltacoronavirus (PDCoV). The recombinant proteins PDCoV-N1 and PDCoV-N2 were expressed via the prokaryotic plasmid pColdII harboring the N gene sequence of the PDCoV strain CH/XJYN/2016. The reactivity and specificity of PDCoV-N1 and PDCoV-N2 with anti-PEDV sera were analyzed after the recombinant proteins were analyzed by SDS-PAGE and purified by the Ni-NTA Superflow Cartridge. Meanwhile, Western blotting and indirect immunofluorescence assay were carried out separately to validate the recombinant proteins PDCoV-N1 and PDCoV-N2. Finally, we established an indirect ELISA method based on the recombinant protein PDCoV-N2 after optimizing the conditions and tested the sensitivity, specificity, and reproducibility of the method. Then, the established method was employed to examine 102 clinical serum samples. The recombinant protein PDCoV-N2 showed low cross-reactivity with anti-PEDV sera. The optimal conditions of the indirect ELISA method based on PDCoV-N2 were as follows: the antigen coating concentration of 1.25 μg/mL and coating at 37 ℃ for 1 h; blocking by BSA overnight at 4 ℃; serum sample dilution at 1:50 and incubation at 37 ℃ for 1 h; secondary antibody dilution at 1:80 000 and incubation at 37 ℃ for 1 h; color development with TMB chromogenic solution at 37 ℃ for 10 min. The S/P value ≥ 0.45, ≤0.38, and between 0.45 and 0.38 indicated that the test sample was positive, negative, and suspicious, respectively. The testing results of the antisera against porcine epidemic diarrhea virus (PEDV), porcine circovirus 2 (PCV2), transmissible gastroenteritis virus (TGEV), foot-and-mouth disease virus (FMDV), and African swine fever virus (ASFV) showed that the S/P values were all less than 0.38. The testing results of the 800-fold diluted anti-PDCoV sera were still positive. The results of the inter- and intra-batch tests showed that the coefficients of variation of this method were less than 10%. Clinical serum sample test results showed the coincidence rate between this method and neutralization test was 94.12%. In this study, an ELISA method for the detection of anti-PDCoV antibodies was successfully established based on the truncated N protein of PDCoV. This method is sensitive, specific, stable, and reproducible, serving as a new method for the clinical diagnosis of PDCoV.
Animals ; Enzyme-Linked Immunosorbent Assay/methods* ; Swine ; Antibodies, Viral/blood* ; Recombinant Proteins/genetics* ; Deltacoronavirus/isolation & purification* ; Coronavirus Infections/virology* ; Swine Diseases/diagnosis* ; Coronavirus Nucleocapsid Proteins ; Sensitivity and Specificity

A new coronavirus (SARS-CoV-2) has been identified as the etiologic agent for the COVID-19 outbreak. Currently, effective treatment options remain very limited for this disease; therefore, there is an urgent need to identify new anti-COVID-19 agents. In this study, we screened over 6,000 compounds that included approved drugs, drug candidates in clinical trials, and pharmacologically active compounds to identify leads that target the SARS-CoV-2 papain-like protease (PLpro). Together with main protease (M
Antiviral Agents/therapeutic use* ; Binding Sites ; COVID-19/virology* ; Coronavirus Papain-Like Proteases/metabolism* ; Crystallography, X-Ray ; Drug Evaluation, Preclinical ; Drug Repositioning ; High-Throughput Screening Assays/methods* ; Humans ; Imidazoles/therapeutic use* ; Inhibitory Concentration 50 ; Molecular Dynamics Simulation ; Mutagenesis, Site-Directed ; Naphthoquinones/therapeutic use* ; Protease Inhibitors/therapeutic use* ; Protein Structure, Tertiary ; Recombinant Proteins/isolation & purification* ; SARS-CoV-2/isolation & purification*

Drugs targeting immune checkpoint are used for cancer treatment, but resistance to single drug may occur. Combination therapy blocking multiple checkpoints simultaneously can improve clinical outcome. Therefore, we designed a recombinant protein rPC to block multiple targets, which consists of extracellular domains of programmed cell death protein 1 (PD-1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4). The coding sequence was inserted into expression vector and stably transfected into HEK293 cells. The culture supernatant was collected and rPC was affinity-purified. Real-time quantitative PCR was used to evaluate the expression levels of ligands for PD-1 and CTLA-4 in several human cancer cell lines. The binding of rPC with cancer cells was examined by immunofluorescence cell staining, the influence of rPC on cancer cell growth was assayed by CCK-8. The results showed that rPC could be expressed and secreted by stably transfected HEK293 cells, the purified rPC could bind to lung cancer NCI-H226 cells which have high levels of ligands for PD-1 and CTLA-4, no direct impact on cancer cell growth could be observed by rPC treatment. The recombinant protein rPC can be functionally assayed further for developing novel immunotherapeutic drugs for cancer.
Animals ; CTLA-4 Antigen ; genetics ; Cell Proliferation ; HEK293 Cells ; Humans ; Lung Neoplasms ; metabolism ; Programmed Cell Death 1 Receptor ; genetics ; Protein Binding ; Protein Domains ; genetics ; Recombinant Fusion Proteins ; genetics ; isolation & purification ; metabolism

OBJECTIVE: To develop methods of extraction and purification of Cterminal NUDT9 homology domain of human transient receptor potential melastatin 2 (TRPM2) channel. METHODS: After sonication and centrifuge of strain Rosetta (DE3) which was induced by isopropylthio-β-D-galactoside, GST-NUDT9-H was collected after the binding of supernatant with GST beads and eluted with reduced glutathione. Then the elution buffer containing fusion protein was purified by size exclusion chromatography after concentration and centrifuge. Finally, with the cleavage of thrombin and binding with the GST beads, NUDT9-H with high purity in supernatant was collected. RESULTS: The GST-NUDT9-H fusion protein was stabilized with lysis buffer containing 0.5% n-dodecyl -β-d-maltoside (DDM), and wash buffer containing 0.025% DDM in size-exclusion chromatography system, and finally the NUDT9-H with high purity was obtained after cleaved by thrombin (1 U/2 mg fusion protein) for 24 h. CONCLUSIONS Due to the poor stability of NUDT9-H, it is necessary to add DDM in extraction and purification buffer to stabilize the conformation of NUDT9-H, so as to increase its yields and purity.
Escherichia coli ; genetics ; Glucosides ; chemistry ; Humans ; Protein Domains ; Protein Stability ; Pyrophosphatases ; chemistry ; genetics ; isolation & purification ; Recombinant Fusion Proteins ; chemistry ; isolation & purification ; TRPM Cation Channels ; chemistry ; isolation & purification ; Thrombin ; metabolism

By using an RAD peptide display system derived from the ATPase domain of recombinase RadA of Pyrococcus furiosus, an anti-hCG antibody-like molecule was prepared by grafting an hCG-binding peptide to the RAD scaffold. After linking to sfGFP gene, a gene of hCG peptide-grafted RAD was synthesized and cloned into a bacterial expression vector (pET30a-RAD/hCGBP-sfGFP). The vector was transformed into Escherichia coli, and expression of the fusion protein was induced. After isolation and purification of the fusion protein, its binding affinity and specificity to hCG were determined by using a process of immunoabsorption followed by GFP fluorescence measurement. A comparison of hCG-binding activity with a similarly grafted single-domain antibody based on a universal scaffold was performed. The measurement of hCG-binding affinity and specificity revealed that the grafted RAD has an optimally high binding affinity and specificity to hCG, which are better than the grafted single-domain antibody. Moreover, the affinity and specificity of grafted RAD molecule are comparable to those of a commercial monoclonal antibody. In addition, the hCG-binding peptide-grafted RAD molecule has a relatively high biochemical stability, making it a good substitute for antibody with potential application.
Antibodies, Monoclonal ; chemistry ; isolation & purification ; metabolism ; Antibody Specificity ; DNA-Binding Proteins ; genetics ; metabolism ; Escherichia coli ; genetics ; Escherichia coli Proteins ; metabolism ; Humans ; Peptides ; Recombinant Fusion Proteins ; genetics ; metabolism

The Brucella mdh gene was successfully cloned and expressed in E. coli. The purified recombinant malate dehydrogenase protein (rMDH) was reactive to Brucella-positive bovine serum in the early stage, but not reactive in the middle or late stage, and was reactive to Brucella-positive mouse serum in the late stage, but not in the early or middle stage of infection. In addition, rMDH did not react with Brucella-negative bovine or mouse sera. These results suggest that rMDH has the potential for use as a specific antigen in serological diagnosis for early detection of bovine brucellosis.
Animals ; Antigens, Bacterial/*immunology ; Brucella abortus/*enzymology/immunology ; Brucellosis/diagnosis/*veterinary ; Cattle ; Cattle Diseases/*diagnosis ; Cloning, Molecular ; Enzyme-Linked Immunosorbent Assay ; Escherichia coli/genetics ; Malate Dehydrogenase/*genetics/*immunology/isolation & purification ; Mice ; Recombinant Proteins/genetics/*immunology

BACKGROUND/AIMS: The relationship between patient survival and biopsy-proven acute rejection (BPAR) in liver transplant recipients with hepatitis C remains unclear. The aims of this study were to compare the characteristics of patients with and without BPAR and to identify risk factors for BPAR. METHODS: We retrospectively reviewed the records of 169 HCV-RNA-positive patients who underwent LT at three centers. RESULTS: BPAR occurred in 39 (23.1%) of the HCV-RNA-positive recipients after LT. The 1-, 3-, and 5-year survival rates were 92.1%, 90.3%, and 88.5%, respectively, in patients without BPAR, and 75.7%, 63.4%, and 58.9% in patients with BPAR (P<0.001). Multivariate analyses showed that BPAR was associated with the non-use of basiliximab and tacrolimus and the use of cyclosporin in LT recipients with HCV RNA-positive. CONCLUSION: The results of the present study suggest that the immunosuppression status of HCV-RNA-positive LT recipients should be carefully determined in order to prevent BPAR and to improve patient survival.
Antibodies, Monoclonal/therapeutic use ; Biopsy ; Cyclosporine/therapeutic use ; Drug Therapy, Combination ; Genotype ; Graft Rejection/mortality/*prevention & control ; Hepacivirus/genetics/isolation & purification ; Hepatitis C/drug therapy/*virology ; Humans ; Immunosuppressive Agents/*therapeutic use ; *Liver Transplantation/adverse effects ; Polymerase Chain Reaction ; RNA, Viral/blood ; Recombinant Fusion Proteins/therapeutic use ; Recurrence ; Retrospective Studies ; Survival Rate ; Tacrolimus/therapeutic use

To construct a bait expression vector containing the duck circovirus Cap gene for use in the yeast two-hybrid system, the whole cap codon-optimized gene was inserted into pGBKT7 vector and confirmed by PCR, restriction enzyme digestion, and sequence analysis. After transformation into a Y2HGold yeast strain, the expression of Cap protein was analyzed by Western blotting. Toxicity and self-activation of the bait protein were detected using different dropout minimal base. PCR reaction, restriction enzyme digestion, and sequencing analyses indicated that the duck circovirus Cap gene was correctly inserted into pG- BKT7. Western blotting showed that the whole Cap protein was expressed. The recombinant bait protein had no toxicity and self-activation. Therefore, the bait vector with the Cap gene was constructed successfully, providing a foundation for future screening for interacting proteins in the yeast two-hybrid system.
Animals ; Capsid Proteins ; genetics ; metabolism ; Circovirus ; classification ; genetics ; isolation & purification ; Cloning, Molecular ; Ducks ; Genetic Vectors ; genetics ; metabolism ; Recombinant Fusion Proteins ; genetics ; metabolism ; Saccharomyces cerevisiae ; genetics ; metabolism ; Two-Hybrid System Techniques