• Animal cells and systems
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• 제15권1호
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• pp.29-36
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• 2011

Insect lysozymes are basic, cationic proteins synthesized in fat body and hemocytes in response to bacterial infections and depolymerize the bacterial cell wall. The c-type lysozyme of the insect Spodoptera litura (SLLyz) is a single polypeptide chain of 121 residues with four disulfide bridges and 17 rare codons and is approximately 15 kDa. The full-length SLLyz cDNA is 1039 bp long with a poly(A) tail, and contains an open reading frame of 426 bp long (including the termination codon), flanked by a 54 bp long 5' UTR and a 559 bp long 3' UTR. As a host for the production of high-level recombinant proteins, E. coli is used most commonly because of its low cost and short generation time. However, the soluble expression of heterologous proteins in E. coli is not trivial, especially for disulfide-bonded proteins. In order to prevent inclusion body formation, GST was selected as a fusion partner to enhance the solubility of recombinant protein, and fused to the amplified products encoding mature SLLyz. The expression vector pGEX-4T-1/rSLLyz was then transformed into E. coli BL21(DE3)pLysS for soluble expression of rSLLyz, and the soluble fusion protein was purified successfully. Inhibition zone assay demonstrated that rSLLyz showed antibacterial activity against B. megaterium. These results demonstrate that the GST fusion expression system in E. coli described in this study is efficient and inexpensive in producing a disulfide-bonded rSLLyz in soluble, active form, and suggest that the insect lysozyme is an interesting system for future structural and functional studies.

• BMB Reports
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• 제32권6호
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• pp.594-598
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• 1999

The Jun and Fos families of eukaryotic transcription factors form heterodimers capable of binding to their cognate DNA enhancer elements. We are interested in searching for inhibitors or antagonists of the binding of the Jun-Fos heterodimer to the activator protein-1 (AP-1) site. The basic-region leucine zipper (bZIP) domain of c-Fos was expressed as a fusion protein with glutathione S-transferase, and allowed to form a heterodimer with the bZIP domain of c-Jun. The heterodimer was bound to glutathione-agarose, to which were added radiolabeled AP-1 nucleotides. After thorough washing, the gel-bound radioactivity was counted. The assay is faster than the coventional electrophoretic mobility shift assay because the gel electrophoresis step and the autoradiography step are eliminated. Moreover, the assay is very sensitive, allowing the detection of picomolar quantities of nucleotides, and is not affected by up to 50% dimethylsulfoxide, a solvent for hydrophobic inhibitors. Curcumin and dihydroguaiaretic acid, recently known inhibitors of Jun-Fos-DNA complex formation, were applied to this Jun-GST-fused Fos system and revealed to decrease the dimer-DNA binding.

• Parasites, Hosts and Diseases
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• 제34권2호
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• pp.135-142
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• 1996

톡소포자충(Toxoplosma gondii) 주요막단백질의 하나인 30 kDa 단백질(p30)의 항원부위를 결정하고자 p30의 아미노산 분석에 따른 친수성 부위 및 혐수성 부위에 맞게 유전자를 증폭하고 발현시켜 항원성을 검토하였다 p30의 절편으로는 p30 전체 p30의 N-말단 Signal Sequence와 C- 탈단의 혐수성 부위를 제거한 S28. S28의 N-말단 2/3부위인 Al9. S28의 C-말단 2/3부위인 Pl9. 528의 N-탈난 1/3부위인 X9 중앙 1/3부위인 Y10 및 C-말단 1/5부위인 Z9로 구성하였다. 각절편에 대한 primer에는 EcoR I의 clampsequence를 포함시켜 중합효소반응으로 증폭시켰으며 G57를 발현하는 pGEX-4T-1 vector에 삽입시킨 후 Eschericha coli(.JM105 strain)에 형질변형시키고 IgG로 각 절편이 GST와 융합단백질로 발현되도록 하였다 SDS-PAGE상에서 p30은 63 kDa. S28는 54 kDa Al9과 Pl9은 각각 45 kDa. X9은 35 kDa. Y10은 36 kDa 및 29은 35 kDa 단백질로 발현되었다. 각각의 단백질은 westemblot상에서 GSTdetectionkit와 잘 반응하여 융합단백질임을 확인하였다. 톡소포자충증 환자 혈청과 westem blot에서 p30. S28 및 Al9은 반응하여 항원성이 인정되었으나 Pl9 . X9, Y10 및 Z9는 반응하지 않았다 따라서. p30의 중간 1/3 부위의 존재하에 N-말단 1/3부위가 항원성을 나타내는 구조적 항원이거나. 첫 1/3부위와 중 간 1/3부위의 경계에 위치한 polypeptide가 항원성을 발현하는 것으로 추정되었다.

• The Korean Journal of Physiology and Pharmacology
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• 제4권6호
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• pp.487-496
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• 2000

Insulin stimulates glucose transport in muscle and fat cells by promoting the translocation of glucose transporter (GLUT4) to the cell surface. Phosphatidylinositide 3-kinase (PI3-kinase) has been implicated in this process. However, the involvement of protein kinase B (PKB)/Akt and $PKC-{\zeta}$, those are known as the downstream target of PI3-kinase in regulation of GLUT4 translocation, is not known yet. An interesting possibility is that these protein kinases phosphorylate GLUT4 directly in this process. In the present study, $PKB-{\alpha}$ and $PKC-{\zeta}$ were added exogenously to GLUT4-containing vesicles purified from low density microsome (LDM) of the rat adipocytes by immunoadsorption and immunoprecipitation for direct phosphorylation of GLUT4. Interestingly GLUT4 was phosphorylated by $PKC-{\zeta}$ and its phosphorylation was increased in insulin stimulated state but GLUT4 was not phosphorylated by $PKB-{\alpha}.$ However, the GST-fusion proteins, GLUT4 C-terminal cytoplasmic domain (GLUT4C) and the entire major GLUT4 cytoplasmic domain corresponding to N-terminus, central loop and C-terminus in tandem (GLUT4NLC) were phosphorylated by both $PKB-{\alpha}$ and $PKC-{\zeta}.$ The immunoblots of $PKC-{\zeta}$ and $PKB-{\alpha}$ antibodies with GLUT4-containing vesicles preparation showed that $PKC-{\zeta}$ was co-localized with the vesicles but not $PKB-{\alpha}.$ From the above results, it is clear that $PKC-{\zeta}$ interacts with GLUT4-containing vesicles and it phosphorylates GLUT4 protein directly but $PKB-{\alpha}$ does not interact with GLUT4, suggesting that insulin-elicited signals that pass through PI3-kinase subsequently diverge into two independent pathways, an Akt pathway and a $PKC-{\zeta}$ pathway, and that later pathway contributes, at least in part, insulin stimulation of GLUT4 translocation in adipocytes via a direct GLUT4 phosphorylation.

• Journal of Microbiology and Biotechnology
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• 제16권9호
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• pp.1429-1433
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• 2006

Application of recombinant protein production and particularly their isotopic enrichment has stimulated development of a range of novel multidimensional heteronuclear NMR techniques. Peptides in most cases are amenable to assignment and structure determination without the need for isotopic labeling. However, there are many cases where the availability of $^{15}N$ and/or $^{13}C$ labeled peptides is useful to study the structure of peptides with more than 30 residues and the interaction between peptides and membrane. CRAMP (Cathelicidin-Related AntiMicrobial Peptide) was identified from a cDNA clone derived from mouse femoral marrow cells as a member of cathelicidin-derived antimicrobial peptides. CRAMP was successfully expressed as a GST-fused form in E. coli and purified using affinity chromatography and reverse-phase chromatography. The yield of the CRAMP was 1.5 mg/l 1. According to CD spectra, CRAMP adopted ${\alpha}$-helical conformation in membrane-mimetic environments. Isotope labeling of CRAMP is expected to make it possible to study the structure and dynamic properties of CRAMP in various membrane systems.

• Journal of Microbiology and Biotechnology
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• 제20권4호
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• pp.727-731
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• 2010

The gene APE0743 encoding the superoxide dismutase (ApSOD) of a hyperthermophilic archaeon Aeropyrum pernix K1 was cloned and overexpressed as a GST fusion protein at a high level in Escherichia coli. The expressed protein was simply purified by the process of glutathione affinity chromatography and thrombin treatment. The ApSOD was a homodimer of 25 kDa subunits and a cambialistic SOD, which was active with either Fe(II) or Mn(II) as a cofactor. The ApSOD was highly stable against high temperature. This thermostable ApSOD is expected to be applicable as a useful biocatalyst for medicine and bioindustrial processes.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1620-1627
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• 2009

The design and expression of an antihypertensive peptide multimer (AHPM), a common precursor of 11 kinds of antihypertensive peptides (AHPs) tandemly linked up according to the restriction sites of gastrointestinal proteases, were explored. The DNA fragment encoding the AHPM was chemically synthesized and cloned into expression vector pGEX-3X. After an optimum induction with IPTG, the recombinant AHPM fused with glutathione S-transferase (GST-AHPM) was expressed mostly as inclusion body in Escherichia coli BL21 and reached the maximal production, 35% of total intracellular protein. The inclusion body was washed, dissolved, and purified by cation-exchange chromatography under denaturing conditions, followed by refolding together with size-exclusion chromatography and gradual dialysis. The resulting yield of the soluble GSTAHPM (34 kDa) with a purity of 95% reached 399 mg/l culture. The release of high active fragments from the AHPM was confirmed by the simulated gastrointestinal digestion. The results suggest that the design strategy and production method of the AHPM will be useful to obtain a large quantity of recombinant AHPs at a low cost.

• Animal cells and systems
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• 제16권6호
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• pp.455-461
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• 2012

Amongst the various antimicrobial peptides, lysozyme plays a central role in initiating and maintaining the antibacterial defense response of insect. Here we propose the biosynthesis and refolding of recombinant lysozyme in Escherichia coli expressed in inclusion body form. The Agrius lysozyme gene was amplified using gene specific primers and then ligated into the pGEX-4T-1 vector, which contained the glutathione S-transferase (GST) gene as a fusion partner. A recombinant lysozyme was expressed in E. coli Rosetta cells using a pGEX-4T-1 expression vector, and the fusion protein was induced by ioporpyl-${\beta}$-D-thiogalactopyranoside (IPTG). The recombinant protein produced as an inclusion body was resolubilized in solubilization buffer, and the resultant solution was dialyzed in refolding buffer. After thrombin cleavage, the recombinant lysozyme was purified by ion exchange chromatography and reverse phase chromatography. The recombinant lysozyme was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis and immunoreactivity against the anti-Agrius lysozyme was observed by western blot analysis of this protein. The recombinant lysozyme displayed antibacterial activity against Bacillus megaterium and Micrococcus luteus, which was confirmed by the inhibition zone assay.

• Bulletin of the Korean Chemical Society
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• 제16권5호
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• pp.401-406
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• 1995

The P. fragi lipase overexpressed in E. coli as a fusion protein of 57 kilodalton (kDa) has been purified through glutathione-agarose affinity chromatography by elution with free glutathione. The general properties of the purified GST-fusion protein were characterized by observing absorbance of released p-nitrophenoxide at 400 nm which was hydrolyzed from the substrate p-nitrophenyl palmitate. The optimum condition was observed at 25 $^{\circ}C$, pH 7.8 with 0.4 ${\mu}g$ of protein and 1.0 mM substrate in 0.6% (v/v) TritonX-100 solution. Also the lipase was activated by Ca+2, Mg+2, Ba+2 and Na+ but it was inhibited by Co+2 and Ni+2. pGEX-2T containing P. fragi lipase gene as expression vector was named pGL191 and used as a template for the site-directed mutagenesis by sequential PCR steps. A Ser-His-Asp catalytic triad similar to that present in serine proteases may be present in Pseudomonas lipase. Therefore, the PCR fragments replacing Asp217 to Arg and His260 to Arg were synthesized, and substituted for original fragment in pGL19. The ligated products were transformed into E. coli NM522, and pGEX-2T harboring mutant lipase genes were screened through digestion with XbaI and StuI sites created by mutagenic primers, respectively. No activity of mutant lipases was observed on the plate containing tributyrin. The purified mutant lipases were not activated on the substrate and affected at pH variation. These results demonstrate that Asp217 and His260 are involved in the catalytic site of Pseudomonas lipase.

• KSBB Journal
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• 제16권2호
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• pp.146-152
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• 2001

rhGH-GST 융합단백질을 사용하여 재조합 대장균 세포 파쇄액으로부터 직접적으로 내포체의 solid-phase 재접힘을 수행할 수 있는 새로운 공정을 개발하였다. 그것은 고체 업자를 제거하는 동시에 초기에 목적딴백질을 흡착 포집할 수 있 는 expanded bed adsorption 크로마토그래피의 장점을 이용한 것이다. 세포 파쇄액 내 용해훤 내포체로부터의 풀린 융합단백질은 expanded bed adsorption 원리에 의해 STREAMLINE DEAE resin에 흡착되고 세포 찌꺼기 등 고체 입자물들은 위 방향 흐름에 의해 효과적으로 제거된다. Urea를 접차적으로 제거함으로써 융합단백질은 고체 matrix 표면에서 재접힘 된 후 염 놓도 구배에 의해 용출된다. 이 새로운 EBA-mediat$\xi$d 재접힘 방법은 응집현상을 획기적으로 줄이고 공정수율윤 향상시킬 뿐 아나라 공정단계 수를 줄일 수 있다. 이 공정은 우리가 알고 있는 한 세계에서 최초로 개발된 공정이며, 현재 single-chain polypeptide, affinity-tagged protein 등과 갈은 다른 행태의 단백질에 EBA를 사용한 재접힘 공정올 적용시키가 위한 연구가 진행되고 있다.