ABSTRACT
Most drugs need to interact with cell membrane to reach the biological target, so that membrane affinity assay is an important early screening step in drug discovery. However, at present, the traditional oil-water distribution method is still used, a new, simple and accurate method for membrane affinity assay is urgently needed. In this study, according to the colorimetric principle, a new assay model based on polydiacetylene vesicles was optimized through a series of experiments including different concentrations of vesicle solution, temperature, or pH reaction environment. On this basis, tetracaine hydrochloride, 2-methylimidazole and histamine were used as model drugs to measure the membrane affinity constants and verify the between-batch precision of the optimized assay model (relative standard deviation less than 5%). In addition, polydiacetylene vesicles were stable for up to 180 days, demonstrating the potential application of the assay model. This strategy is simple, stable, reliable, with high reproducibility, low cost and easy to promote, which provided a new tool and a new direction for the high-throughput assay of membrane affinity.
ABSTRACT
ObjectiveTo prepare high specific monoclonal antibodies(mAbs) against BP26 of Brucella(B.)melitensis.Methods A recombinant plasmid pET-28a-BP26 was constructed and transformed into competent Escherichia coli BL21 (DE3),and then the bacteria were induced by 1 mmol/L isopropylthio-β-D-galactoside (IPTG).After induction,the recombinant BP26 protein (rBP26) was purified by sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PGAE) and nickel ion affinity chromatography(Ni-NTA).Mice were inoculated with rBP26 antigens for three times at 2-week intervals.The first subcutaneous injection contained 100 μg rBP26 with 0.1 ml complete Freund adjuvant.The second subcutaneous injection was 50 μg rBP26 with 0.1 ml incomplete Freund adjuvant.The antibody titers to rBP26 were determined 2 weeks after each reimmunization.Three days before cell fusion,the mice with the highest titer were intraperitoneally injected with 50 μg rBP26 in 0.1 ml PBS.Pre- and post-immunization sera were collected and used as negative or positive controls for screening mAbs.Mice with the highest titer were sacrificed and spleen cells were isolated.The spleen cells of rBP26 immunized mice were fused with SP2/0 myeloma cells in a ratio of 5 ∶ 1 by polyethylene glycol(PEG) 1450.Antibody-producing hybridomas were primarily screened by an indirect enzyme-linked immunosorbnent assay(ELISA) with rBP26.Reactive hybridomas were subcloned for 3 times,then the strains of hybridoma cells secreting antibodies against BP26 were obtained.Supernatant of cloned hybridoma cultures was collected for mAb analyses.These mAbs were named by the hybridoma clone number and tested their reactivity to membrane proteins extracted(NMP) from B.melitensis vaccine strain(M5-90) by Western blotting and Dot-ELISA.mAbs isotyping and kappa(κ) or lambda(λ) light chain was identified by Mouse Monoclonal Antibody Isotyping Kit.Results A total of two mAbs reactive to rBP26 of B.melitensis were selected from antibody screening hybridomas by indirect-ELISA.The two mAbs were named 3C3 and 5A5,and identified as IgG1 (κ) and IgG2(κ),respectively.They could react with NMP from M5-90.Conclusions Results of identification show that two mAbs against rBP26 can be produced.The two mAbs can recognize natural BP26 protein,giving the experimental materials for further research on identification of its epitopes.
ABSTRACT
The latest progress in research on constituents and pharmacological activities of sarcotestas of Ginkgo biloba has been studied. The main constituents in sarcotestas of G. biloba include flavones, ginkgolides, alkylphenols, polysaccharides and amino acids, etc. They show the following activities, such as bacteriostatic, bactericidal and pesticidal activities, antitumor and mutagenic, carcinogenic effects, antianaphylaxis and allergenic activity, effects on immunologic function, scavenging free radical, antisenile action, etc. The problems at present and the reseach direction for the future on sarcotestas of G. biloba have been put forward.