• Journal of Microbiology and Biotechnology
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• v.18 no.8
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• pp.1475-1481
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• 2008

B3 antibody specifically binds the $Lewis^Y$-related carbohydrate antigen of many carcinomas, and it is used as a model antibody in this study. In a previous study, the Fab fragment of the antibody was fused to a 38 kDa truncated form of Pseudomonas exotoxin A, PE38, to make Fab-PE38, where PE38 is fused to the Fd fragment of the Fab domain. This parent monomer molecule, Fab-PE38, had no cysteine in the hinge region, and it could not make a disulfide bond to form a disulfide bond bridged homodimer. In this study, we constructed three different kinds of divalent Fab-toxin fusion homodimers where the toxin is fused to the light chain of Fab, $(Fab-PE38fl)_2$. In addition to the PE38 toxin fused to the light chain, these three molecules have different hinge sequences hi, h2, and h3 making Fabh1-, Fabh2-, and Fabh3-PE38fl monomers, respectively. These hinges contain only one cysteine on different positions of the hinge sequence. The disulfide bond between the hinge region of two monomers forms homodimers $(Fabh1-PE38fl)_2$, $(Fabh2-PE38fl)_2$, and $(Fabh3-PE38fl)_2$. The refolding yields of these dimers were 5-16-fold higher than a previously constructed dimer where the PE38 was fused to the Fd fragment $(Fabh2-PE38)_2$ [8]. Our data suggest that the steric repulsion between the two PE38s in $(Fabh1-PE38)_2$ during disulfide bridge formation is relieved by fusing it at the end of the light chain. The best cytotoxicity value of these dimers showed about 2.5-fold higher on an MCF7 cell line than that of the monovalent reference molecule in ng/ml scale, which is 15-fold higher in pM scale.

• Korean Journal of Microbiology
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• v.55 no.3
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• pp.199-205
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• 2019

Yeast two-hybrid (Y2H) technique has been used to study protein-protein interactions, but its application particularly to a large-scale analysis of protein interaction networks, is limited by the fact that the technique is labor-intensive, based on scoring colonies on plate. Here, we develop a new reporter for the measurement of the protein-protein interactions by flow cytometry. The yeast harboring interacting proteins can also be enriched by fluorescence-activated cell sorting (FACS) or magnetic-activated cell sorting (MACS). When two interacting proteins are present in the same yeast cell, a reporter protein containing 10 tandem repeats of c-myc epitope becomes localized on the surface of the cell wall, without affecting cell growth. We successful measured the surface display of c-myc epitope upon interacting p53 with SV40 T antigen by flow cytometry. Thus, the newly developed Y2H assay based on the display of c-myc repeat on yeast cell wall could be used to the simultaneous analysis of multiple protein-protein interactions without laborious counting colonies on plate.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.5
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• pp.636-642
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• 2009

The corpus luteum (CL) is a transient endocrine gland that produces progesterone, a product required for the establishment and maintenance of pregnancy. In the absence of pregnancy, the production of progesterone in the CL decreases and the structure itself regresses in size. The life span and function of the CL are regulated by complex interactions between stimulatory (luteotrophic) and inhibitory (luteolytic) mediators. When an ovum is released from a mature follicle, angiogenesis and rapid growth of follicular cells form the CL. The purpose of the present study was to determine whether steroidogenesis, proliferation, and hypoxiarelated proteins are expressed in caprine CL. The expression of proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor (VEGF), and hypoxia-inducible factor $1{\alpha}$ (HIF-$1{\alpha}$) were determined in caprine CL during the estrous cycle. Cytochrome P450 side chain cleavage protein did not vary significantly during the estrous cycle; however, there was an increased expression of $3{\beta}$ -hydroxysteroid dehydrogenase in the early and middle stages, which rapidly decreased in the late stage. The same observations were made with respect to steroidogenic acute regulatory protein. Variations in progesterone content and expression of PCNA, HIF-$1{\alpha}$, and VEGF were consistent with this result. Thus, the steroidogenic proteins, PCNA, HIF-$1{\alpha}$, and VEGF in caprine CL are dependent on the stage of the estrous cycle.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.1
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• pp.106-115
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• 2010

Phosphorylated dextran (P-Dex) is an acidic polysaccharide that functions as an immune adjuvant. P-Dex is known to regulate immune response by maintaining a balance between Th1 and Th2 cells in vitro, and thus may also be important in the control of allergic reactions. In the current study, we report the optimum conditions required for the efficient phosphorylation of dextran without toxicity. We found that when dextran was heated at 160${^{\circ}C}$ for 24 h in phosphate buffer (pH 5.0), the resulting P-Dex demonstrated the highest phosphorus content (6.8%). We also report that P-Dex enhances mitogenic activity in mouse splenocytes and induces expression of CD69 and CD86 on the surface of B cells and dendritic cells (DC) in vitro. Oral administration of P-Dex to ovalubmin (OVA)-immunized mice was found to reduce antigen-induced cell proliferation and suppress the expression of CD86 on Th2-inducing DC via exogenous OVA stimulation. P-Dex was also found to increase IL-10 expression in the splenocytes of treated mice. These findings suggest that oral administration of P-Dex increases immunological tolerance and improves the specificity of immunological response to specific antigens.

• KSBB Journal
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• v.14 no.2
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• pp.241-247
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• 1999

Experimental studies were carried out to optimize the culture conditions of Corynebacterium diphtheriae for the production of diphtheria toxin. A new media which does not contain any meat digest products was selected. The main ingredient of new medium was enzymatic digests of casein known as NZ-Case. In fermenter experiments, the toxin production was increased with the increase of cell growth. The optimum initial pH of media, air flow rate and agitation speed were 7.0, 0.22, vvm and 400 rpm, respectively. The contents of iron and calcium-phosphate precipitate were important for maximal cell growth and toxin production. The optimum concentration of iron was 0.3 mg/L and calcium-phosphate precipitate could serve in gradual supply of iron to maintain the optimal culture condition which is required for enhanced yield of toxin production. In potency test, the potency of toxoid from fermentor culture was higher than that from static culture. When diphtheria toxin is produced by fermentor culture, it is possible to produce higher levels of toxin and better toxoid quality in terms of safety, yield, productivity and immunity.

• Journal of Life Science
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• v.28 no.6
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• pp.753-763
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• 2018

Cysteine cathepsins are lysosomal enzymes that belong to the papain family and can induce the degradation of damaged proteins through the endo-lysosomal pathway. It is highly upregulated in many cancers by regulating gene amplification and transcriptional, translational, and post-transcriptional modifications. Cathepsin S is part of the cysteine cathepsin family. Many studies have demonstrated that cathepsin S not only plays a specific role in MHC class II antigen presentation but also plays a crucial role in cancers. Cathepsin S is more stable at a neutral pH compared to other cysteine cathepsins, which supports the importance of cathepsin S in disease microenvironments. Therefore, the dysregulation of cathepsin S has participated in a variety of pathological processes, including cancer, arthritis, and cardiovascular disease. Furthermore, a decrease or depletion in the expression of cathepsin S has been implicated in the processes of tumor growth, invasion, metastasis, and angiogenesis. Taken together, cathepsin S has been suggested as an attractive therapeutic target for cancer therapy. In this review, the known involvement of cathepsin S in diseases, particularly with respect to recent work indicating its role in cancer therapy, is examined. An overview of current literature on the inhibitors of cathepsin S as a therapeutic target for cancer is also provided.

• BMB Reports
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• v.37 no.3
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• pp.314-319
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• 2004

Flounder (Paralichthys olivaceus) Immunoglobulins (Igs) were purified from the serum of mouse IgG-immunized flounder by using affinity chromatography. Under denaturing conditions in SDS-PAGE, the flounder Igs appeared to be composed of 2 heavy (H) chains (72 and 77 kDa) and two light (L) chains (26 and 28 kDa). Monoclonal antibodies (MAbs) were produced by the fusion of myeloma cells (SP2/0) with Balb/c mouse spleen cells that were previously sensitized against affinity-purified flounder Igs. In a Western blot analysis, the produced MAbs, FIM511, FIM519, and FIM562 recognized both the 72 and 77 kDa H chains, 26 kDa, and 28 kDa L chain, respectively. Mouse antiserum against flounder Igs reacted more strongly with the L chain of 28 kDa than with 26 kDa, suggesting that the 28 kDa molecule is more immunogenic than the 26 kDa L chain molecule. In a FACS analysis, the ratios of the Ig+ cell population in the flounder head kidney and spleen cells were 49% and 24%, respectively. Unexpectedly, however, the ratios of the Ig+ B-like cell population in the flounder were not significantly augmented, even after the immunization of an immunogenic antigen. This suggests that the humoral immune response in fish could be considerably different from that in mammals. The produced MAbs in this study would be useful in characterizing flounder Ig+ B-like cells and in developing flounder Ig detecting an immunoassay system.

• Smart Structures and Systems
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• v.8 no.1
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• pp.17-37
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• 2011

The microcantilever (MCL) sensor is one of the most promising platforms for next-generation label-free biosensing applications. It outperforms conventional label-free detection methods in terms of portability and parallelization. In this paper, an overview of recent advances in our understanding of the coupling between biomolecular interactions and MCL responses is given. A dual compact optical MCL sensing platform was built to enable biosensing experiments both in gas-phase environments and in solutions. The thermal bimorph effect was found to be an effective nanomanipulator for the MCL platform calibration. The study of the alkanethiol self-assembly monolayer (SAM) chain length effect revealed that 1-octanethiol ($C_8H_{17}SH$) induced a larger deflection than that from 1-dodecanethiol ($C_{12}H_{25}SH$) in solutions. Using the clinically relevant biomarker C-reactive protein (CRP), we revealed that the analytical sensitivity of the MCL reached a diagnostic level of $1{\sim}500{\mu}g/ml$ within a 7% coefficient of variation. Using grazing incident x-ray diffractometer (GIXRD) analysis, we found that the gold surface was dominated by the (111) crystalline plane. Moreover, using X-ray photoelectron spectroscopy (XPS) analysis, we confirmed that the Au-S covalent bonds occurred in SAM adsorption whereas CRP molecular bindings occurred in protein analysis. First principles density functional theory (DFT) simulations were also used to examine biomolecular adsorption mechanisms. Multiscale modeling was then developed to connect the interactions at the molecular level with the MCL mechanical response. The alkanethiol SAM chain length effect in air was successfully predicted using the multiscale scheme.

• Journal of Microbiology and Biotechnology
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• v.10 no.1
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• pp.56-62
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• 2000

The hpa gene genetically linked to the ctxa2b gene was cloned into the pTED expression vector, and the constructed pTEDhpa/ctxa2b was transformed into Excherichia coli. The fusion protein, the adhesin fused to the cholera toxin subunit A2B (CTXA2B) subunit, was expressed to high levels as inclusion bodies in E. coli. The expressed protein was partially purified by washing the inclusion bodies with working solution containing 8M Urea and 0.1M DTT. Refolding of denatured fusion protein was carried out in the presence of glutathione redox buffer. The refolded fusion protein was purified by size exclusion chromatography. The expressed fusion protein was verified by SDS-PAGE, western blotting with antibodies to both antigenic components of adhesin and cholera toxin subunit B (CTXB), and its N-terminal amino acid sequence was analyzed. The orderly assembled fusion protein was confirmed by modified Gm1-ganglioside ELISA with Abs to adhesin. The results indicate that the purified fusion protein is an Adhesin/CTXA2B protein containing the H. pylori adhesin and $G_{m1}4-ganglioside binding activity of CTXB and the expressed fusion protein in E. coli could be easily purified by the refolding process, Its molecular weight was 168kDa as estimated by size exclusion chromatography. The Adhesin/CTXA2B protein may be used as a candidate antigen for oral immunization against H. pylori.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.12
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• pp.1791-1797
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• 2007

A study was conducted with 70 Hanwoo (Korean cattle) for genotyping bovine leukocyte antigen (BoLA)-DRB3.2 gene by using the polymerase chain reaction (PCR) and sequence based typing (SBT). Two-step PCR was carried out for amplifying a 284 bp fragment of the target gene and the PCR products were digested with three restriction enzymes namely RsaI, BstYI and HaeIII. Seventeen alleles were detected with frequencies ranging from 1.43 to 18.57% and one (x'aa) of these alleles was identified as a new allele that has not been reported before. The frequency of the new x'aa allele identified in this breed was 12.86%. In addition, the seven most frequently observed alleles (DRB3.2 *10, *15, *16, *26, *27, *54 and x'aa) accounted for 74.28% of the alleles in this population. The phylogenetic tree showed that the BoLA-DRB3.2 allele sequences of Hanwoo were shared with other Bos taurus breeds and no specific clade for Hanwoo was identified. It indicates high heterogeneity of the BoLA-DRB3 gene in this population and may give some ideas for breeding animals having better disease resistance.