• BMB Reports
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• 제31권5호
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• pp.515-518
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• 1998

Adhesive interaction of the platelet glycoprotien IIb-IIIa (GP IIb-IIIa) with a plasma protein, such as fibrinogen, plays an important role in thrombosis and hemostasis. The specific sequence Arg-Gly-Asp (RGD) is critical for the binding of fibrinogen to platelet. To examine and characterize the GP IIb-IIIa antagonist from natural sources, we have developed a simple enzyme-linked immunosorbant assay (ELISA) system. The GP IIb-IIIa complex was purified to homogeneity from platelet Iysates by the combination of two affinity chromatographic methods using the synthetic RGD peptide (GRGDSPK)-immobilized Sepharose and wheat germ lectin-Sepharose. The synthetic peptide GRGDSP inhibits GP IIb-IIIa binding to immobilized fibrinogen with an $IC_{50}$ of $1.5\;{\mu}M$. Venoms of three different snake species and a Korean scolopendra extract have strong antagonistic activities for the binding of human fibrinogen to the platelet GP IIb-IIIa complex. The $IC_{50}$ values of the snake venom s and scolopendra were in the range of $5.5\;{\mu}g$ to $60\;{\mu}g$. These results provide meaningful information for developing antiplatelet agents.

• 식물조직배양학회지
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• 제27권5호
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• pp.375-377
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• 2000

It is now generally accepted that a phosphoinositide cycle is involved in the transduction of a variety of signals in plant cells. In animal cells, the hydrolysis of phosphatidyl-4,5-bisphosphate catalysed by phosphatidylinositol - specific phospholipase C yields to D-myo-inositol - 1,4,5-trisphosphate and diacylglycerol, which are well known second messengers. The binding of InsP$_3$to a receptor located on the endoplasmic reticulum triggers a calcium release from the endoplasmic reticulum. We have detected and partially characterised key components of phosphoinositide signaling. First, tobacco microsomal fraction and plasma membrane PI-PLC. Consecutively, using a radioligand binding assay we have identified a $Ca^{2+}$ -dependent high affinity InsP$_3$binding site in microsomal membrane fraction vesicle preparation and then we have measured inositol-1,4,5-trisphosphate induced calcium release from tobacco microsomal fraction. These findings suggest that phosphoinositide signaling system is present and operates in the tobacco suspension culture.e.

• Molecular & Cellular Toxicology
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• 제2권2호
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• pp.106-113
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• 2006

Phthalate analogues are a plasticizer and solvent used in industry. Phthalates were classified in the category of "suspected" endocrine disruptors. The purpose of our study was to screen and elucidate the endocrine disrupting activity of seven phthalate analogues. E-screen assay was performed in MCF-7 human breast cancer cells with seven phthalate analogues. In this cell proliferation assay, benzyl butyl phthalate (BBP) and dibutyl phthalate (DBP) showed high estrogenic activity. Their relative proliferation efficiencies (RPE) were 109 and 106%, respectively. In vitro estrogen receptor (ER) binding assay, BBP, di-n-octyl phthalate (DOP) and dinonyl phthalate (DNP) showed weak relative binding affinity (RBA: 0.02%) compared to $17{\beta}-estradiol\;(E2)$ (RBA: 100%). In uterotrophic assay, E2 produced a significant increase, whereas four tested phthalate analogues had potential estrogenic effects in vitro did not increased in uterus weight in immature rats. From these results, we demonstrated that phthalate analogues exhibit weak estrogenic activity in vitro assays at high concentrations. Although phthalates induced an increase in MCF-7 cell proliferation by an estrogenic effect, they could not induce a uterus weight increase in vivo. From these, we may suggest that these phthalate analogues are easily metabolized to inactive forms in vivo. Further investigation in other in vitro and in vivo experimental systems might be required.

• Preventive Nutrition and Food Science
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• 제21권4호
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• pp.323-329
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• 2016

Achyranthes japonica Nakai (AJN) water extract has a variety of physiological properties, including anti-diabetic, anti-cancer, anti-inflammatory, anti-microbial, and anti-oxidative activities. In the present study, the inhibitory effects of AJN extract were investigated in high affinity immunoglobulin E receptor ($Fc{\varepsilon}RI$)-mediated KU812F cells activation. AJN extract showed suppressive effects on histamine release and intracellular calcium [$Ca^{2+}$]i elevation from anti$Fc{\varepsilon}RI$ antibody (CRA-1)-stimulated cells in a dose-dependent manner. Flow cytometric analysis showed that AJN extract treatment caused a dose-dependent decrease in the cell surface $Fc{\varepsilon}RI$ expression and the binding between the cell surface $Fc{\varepsilon}RI$ and the IgE antibody. Moreover, reverse transcription-polymerase chain reaction analysis showed that levels of the mRNA for the $Fc{\varepsilon}RI$ ${\alpha}$ chain was decreased by treatment with AJN extract. These results indicate that AJN extract may exert anti-allergic effects via the inhibition of calcium influx and histamine release, which occurs as a result from the downregulation of the binding of IgE antibody to cell surface $Fc{\varepsilon}RI$. This mechanism may occur through $Fc{\varepsilon}RI$ expression inhibition.

• 한국지하수토양환경학회지:지하수토양환경
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• 제16권6호
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• pp.122-132
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• 2011

Mercury accumulates in biota mainly as methylmercury. In nature, methylmercury shows high affinity to organic matter and $CH_3Hg^+$-organic matter complexation affects the mobility and bioavailabiity of methylmercury. In this study, we examined the methylmercury binding sites in an aquatic humic acid as affected by the pH condition using Hg $L_{III}$-edge extended X-ray absorption fine structure (EXAFS). We evaluated methylmercury binding humic ligands using methylmercury-thiol, methylmerury-carboxyl, and methylmercury-amine complexation models. When $CH_3Hg^+$-to-humic reduced sulfur ratio is 0.3, we found that most of $CH_3Hg^+$ binds to thiol ligands at pH 5 and 7. At pH 7, however, some carboxyl or amine ligand contribution is observed, unlike at pH 5 where $CH_3Hg^+$ almost exclusively binds to thiol ligands. The carboxyl or amine ligand contribution may indicate that some types of thiol ligands in the natural organic matter have relatively low complexation constants or acid dissociation constants compared to those of some carboxyl or amine ligands. Analysis results indicate that ~0.2 fraction of methylmercury binds to amine or carboxyl ligands and ~0.8 to thiol ligands at pH 7.

• Bulletin of the Korean Chemical Society
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• 제24권12호
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• pp.1799-1804
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• 2003

Acetolatate synthase(ALS) catalyzes the first common step in the biosynthesis of valine, leucine, isoleucine in plants and microorganisms. ALS is the target of several classes of herbicides, including the sulfonylureas, the imidazolinones, and the triazolopyrimidines. To elucidate the roles of arginine residues in tobacco ALS, chemical modification and site-directed mutagenesis were performed. Recombinant tobacco ALS was expressed in E. coli and purified to homogeneity. The ALS was inactivated by arginine specific reagents, phenylglyoxal and 2,3-butanedione. The rate of inactivation was a function of the concentration of modifier. The inactivation by butanedione was enhanced by borate, and the inactivation was reversible on removal of excess butanedione and borate. The substrate pyruvate and competitive inhibitors fluoropyruvate and phenylpyruvate protected the enzyme against inactivation by both modifiers. The mutation of well-conserved Arg198 of the ALS by Gln abolished the enzymatic activity as well as the binding affinity for cofactor FAD. However, the mutation of R198K did not affect significantly the binding of FAD to the enzyme. Taken together, the results imply that Arg198 is essential for the catalytic activity of the ALS and involved in the binding of FAD, and that the positive charge of the Arg is crucial for the interaction with negatively charged FAD.

• Archives of Pharmacal Research
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• 제16권4호
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• pp.305-311
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• 1993

$Na^+,K^+$-ATPase activity, $Na^+$-dependent phosphorylation, and $[^3H]$ ouabain binding in sarcolemma prepared from 4 week old spontaneously hypertensive rat(SHR) ventricles were compared to the same parameters in sarcolemma from age matched nomotensive Wister-Kyoto (WKY) rat ventricles to examine whether the reduced myocardial $Na^+$-pump activity in SHR is an inherited enzymatic defect or a second phenomenon due to sustained hypertension. The total body weights, ventricular weights, and blood pressures were the same for SHR and WKY. No significant differences in sarcolemmal protein content and protein recovery were noted between the two groups. Sarcolemma isolated from SHR ventricles showed significantly less $Na^+,K^+$-ATPase activity ande number of phosphorylation sites when compared to sarcolemma from the WKY ventricles. Equilibrium binding of $[^3H]$ouabain and the tumover number of myocardial $Na^+,K^+$-ATPase, however, were the same for both groups. These reults indicate that the low affinity $(\alpha,\;or\;\alpha^1)\;\alpha$ isoform is the same in ventricles of SHR and WKY. The reduced amount of isoform of the $Na^+,K^+$-ATPase inprehypetensive SHR ventricles may play some role in the development of hypertension.

• Biomolecules & Therapeutics
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• 제29권5호
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• pp.519-526
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• 2021

In a search for effective PPAR-γ agonists, 110 clinical drugs were screened via molecular docking, and 9 drugs, including parecoxib, were selected for subsequent biological evaluation. Molecular docking of parecoxib to the ligand-binding domain of PPAR-γ showed high binding affinity and relevant binding conformation compared with the PPAR-γ ligand/antidiabetic drug rosiglitazone. Per the docking result, parecoxib showed the best PPAR-γ transactivation in Ac2F rat liver cells. Further docking simulation and a luciferase assay suggested parecoxib would be a selective (and partial) PPAR-γ agonist. PPAR-γ activation by parecoxib induced adipocyte differentiation in 3T3-L1 murine preadipocytes. Parecoxib promoted adipogenesis in a dose-dependent manner and enhanced the expression of adipogenesis transcription factors PPAR-γ, C/EBPα, and C/EBPβ. These data indicated that parecoxib might be utilized as a partial PPAR-γ agonist for drug repositioning study.

• Biomolecules & Therapeutics
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• 제22권4호
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• pp.363-369
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• 2014

Synthetic cannabinoids (CBs) such as the JWH series have caused social problems concerning their abuse liability. Because the JWH series produces euphoric and hallucinogenic effects, they have been distributed illegally under street names such as "Spice" and "Smoke". Many countries including Korea have started to schedule some of the JWH series compounds as controlled substances, but there are a number of JWH series chemicals that remain uncontrolled by law. In this study, three synthetic CBs with different binding affinities to the $CB_1$ receptor (JWH-073, 081, and 210) and ${\Delta}^9$-tetrahydrocannabinol (${\Delta}^9$-THC) were evaluated for their potential for psychological dependence. The conditioned place preference test (unbiased method) and self-administration test (fixed ratio of 1) using rodents were conducted. $K_i$ values of the three synthetic cannabinoids were calculated as supplementary data using a receptor binding assay and overexpressed $CB_1$ protein membranes to compare dependence potential with $CB_1$ receptor binding affinity. All mice administered JWH-073, 081, or 210 showed significantly increased time spent at unpreferred space in a dose-dependence manner in the conditioned place preference test. In contrast, all tested substances except ${\Delta}^9$-THC showed aversion phenomenon at high doses in the conditioned place preference test. The order of affinity to the $CB_1$ receptor in the receptor binding assay was JWH-210 > JWH-081 >> JWH-073, which was in agreement with the results from the conditioned place preference test. However, no change in self-administration was observed. These findings suggest the possibility to predict dependence potential of synthetic CBs through a receptor binding assay at the screening level.

• 미생물학회지
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• 제54권4호
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• pp.330-342
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• 2018

Streptavidin (STR)과 Biotin system은 Biotin의 Streptavidin에 대한 높은 비공유 친화력(non-covalent affinity; $K_D=10^{-14}M$)과 4 Biotin 결합부위를 갖는 Streptavidin의 tetramer 구조로 인해 복수의 항원결합부위 및 복수의 항원특이성을 갖는 항체를 제조할 수 있기 때문에 가장 활발하게 연구되고 있다. 이 system을 활용하기 위해 우리는 Streptomyces avidinii 염색체 DNA로부터 PCR을 통해 Streptavidin (STR) 유전자를 증폭하고 이를 TRAIL (tumor necrosis factor ${\alpha}$ related apoptosis induced ligand) receptor인 death receptor 4 (DR4)에 특이적으로 결합하는 hAY4 single-chain Fv 항체유전자에 융합시켰다. 대장균에서 발현시킨 STR에 융합된 hAY4 ScFv (hAY4-STR) 항체는 가열시킨 SDS-PAGE에서 43 kDa monomer를 나타내었다. 그러나 가열하지 않은 SDS-PAGE와 Size-exclusion chromatography에서는 tetramer인 172 kDa을 나타내었는데 이는 hAY4 ScFv-STR 항체가 STR의 자연적인 비공유결합에 의해 유도된 tetramer를 형성하고 있음을 나타내고 있다. 본 융합 단백질은 Ouchterlony assay와 ELISA에서 보여주는 것처럼 자연 Streptavidin과 유사한 Biotin 결합력을 유지하고 있었다. ELISA와 Westernblot을 이용하여 정제된 hAY4-STR 융합항체의 DR4 항원결합력 또한 확인하였다. 게다가 표면 플라즈몬 공명(surface plasmon resonance) 분석에서 hAY4 ScFv-STR tetramer는 tetramerization에 의해 hAY4 ScFv monomer보다 60배 더 높은 항원결합력을 나타내었다. 요약하면 hAY4 ScFv-STR 융합단백질은 E. coli에서 soluble tetramer로 성공적으로 발현 및 정제되었으며 Biotin과 DR4 항원에 동시에 결합함을 보여 주었다. 이는 bifunctional and tetrameric ScFv 항체를 제조 할 수 있음을 제시해 주고 있다.