• 제목/요약/키워드: Ligand Effects

검색결과 404건 처리시간 0.027초

팔라듐 나노입자가 담지된 메조포러스 실리카의 제조와 이를 이용한 Suzuki Cross-Coupling 반응의 적용연구 (Synthesis of Palladium Nanoparticles Encapsulated in Phosphine Ligand-Grafted Mesoporous Silicas and Their Application to Suzuki Cross-Coupling Reaction)

  • 김상욱;주진
    • 청정기술
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    • 제17권1호
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    • pp.13-18
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    • 2011
  • 포스핀(phosphine) 리간드(ligand)가 도포된 메조포러스 실리카(mesoporous silicas)에 팔라듐 나노입자를 도입하여 새로운 팔라듐(Pd) 불균일 촉매(heterogeneous catalyst)를 제조하였다. 제조된 촉매는 브롬화벤젠 유도체(bromobenzene derivatives)들의 Suzuki cross-coupling 반응에 대하여 뛰어난 촉매활성을 나타내었고 촉매를 두 번째 사용하였을 때는 수율이 감소하였다.

Effects of Co-Expression of Liver X Receptor β-Ligand Binding Domain with its Partner, Retinoid X Receptor α-Ligand Binding Domain, on their Solubility and Biological Activity in Escherichia coli

  • Kang, Hyun
    • Journal of Microbiology and Biotechnology
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    • 제25권2호
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    • pp.247-254
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    • 2015
  • In this presentation, I describe the expression and purification of the recombinant liver X receptor β-ligand binding domain proteins in E. coli using a commercially available double cistronic vector, pACYCDuet-1, to express the receptor heterodimer in a single cell as the soluble form. I describe here the expression and characterization of a biologically active heterodimer composed of the liver X receptor β-ligand binding domain and retinoid X receptor α-ligand binding domain. Although many of these proteins were previously seen to be produced in E. coli as insoluble aggregates or "inclusion bodies", I show here that as a form of heterodimer they can be made in soluble forms that are biologically active. This suggests that co-expression of the liver X receptor β-ligand binding domain with its binding partner improves the solubility of the complex and probably assists in their correct folding, thereby functioning as a type of molecular chaperone.

Does ginsenoside act as a ligand as other drugs do?

  • Nah, Seung-Yeol
    • 고려인삼학회:학술대회논문집
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    • 고려인삼학회 2005년도 창립30주년기념 추계 학술대회 및 정기총회
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    • pp.32-40
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    • 2005
  • The last two decades have shown a marked expansion in publications of diverse effects of Panax ginseng. Ginsenosides, as active ingredients of Panax ginseng, are saponins found in only ginseng. Recently, a line of evidences shows that ginsenosides regulate various types of ion channel activity such as Ca$^{2+}$, K$^+$, Na$^+$, Cl$^-$, or ligand gated ion channels (i.e. 5-HT$_3$, nicotinic acetylcholine, or NMDA receptor) in neuronal, non-neuronal cells, and heterologously expressed cells. Ginsenosides inhibit voltage-dependent Ca$^{2+}$, K$^+$, and Na$^+$ channels, whereas ginsenosides activate Ca$^{2+}$-activated Cl$^-$ and Ca$^{2+}$-activated K$^+$ channels. Ginsenosides also inhibit excitatory ligand-gated ion channels such as 5-HT$_3$. nicotinic acetylcholine, and NMDA receptors. This presentation will introduce recent findings on the ginsenoside-induced differential regulations of ion channel activities as a ligand as other drugs do.

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Neuroprotective Effects of Lithium on NMDA-induced Excitotoxicity in Mouse Cerebrum

  • Kwon, Gee-Youn;Kim, Soo-Kyung
    • The Korean Journal of Physiology and Pharmacology
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    • 제10권3호
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    • pp.111-121
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    • 2006
  • Neuroprotective properties of lithium were evaluated by using in vivo NMDA excitotoxicity model. Systemic injection of NMDA to young mice induced neuronal apoptosis mediated by both TNFR-l and Fas ligand, and long-term lithium treatment showed noticeable neuroprotection against NMDA-induced excitotoxicity: NMDA-damaged neurons expressed several apoptosis-related gene products such as TNFR-l, Fas ligand, and caspase-3, and these gene expressions were not found in the brain of mice chronically treated with lithium. Therefore, it is highly likely that the protection offered by chronic lithium treatment occurred at far upstream of caspase activation, since the chronic lithium treatment increased the expression of Bcl-2, an important antiapoptotic gene known to act upstream of caspase cascade. Timm's histochemistry indicated the complete blockade of the NMDA insults by the treatment. There was no indication of axonal regeneration, which follows synaptic degeneration induced by neuronal damage. Furthermore, this study reports for the first time that TNFR-l and Fas ligand are involved in neuroprotective effects of lithium in NMDA-induced neuronal apoptosis.

Effects of Ligand-exchanged Cadmium Selenide Nanoparticles on the Performance of P3HT:PCBM:CdSe Ternary System Solar Cells

  • Park, Eung-Kyu;Fu, Honghong;Choi, Mijung;Luan, Weiling;Kim, Yong-Sang
    • Bulletin of the Korean Chemical Society
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    • 제34권8호
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    • pp.2321-2324
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    • 2013
  • An improved hybrid solar cell was obtained by focusing on the effects of ligand for CdSe nanoparticles, in the active layers. The performance was compared by mixing nanoparticles capped with pyridine or oleic acid for the acceptor material into poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester based active layer. The solar cells with pyridine capped CdSe nanoparticles showed a power conversion efficiency of 2.96% while oleic acid capped CdSe nanoparticles showed 2.85%, under AM 1.5G illumination. Formation of percolation pathways for carrier transport and a reduction in the hopping event resulted in better performance of pyridine capped nanoparticles.

Single and Dual Ligand Effects on Gene Expression Changes in Mouse Macrophage Cells

  • Choi Sang-Dun;Seo Jeong-Sun
    • Genomics & Informatics
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    • 제4권2호
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    • pp.57-64
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    • 2006
  • We identified differentially expressed genes in RAW264.7 cells in response to single and double ligand treatments (LPS, $IFN{\gamma}$, 2MA, LPS plus $IFN{\gamma}$, and LPS plus 2MA). The majority of the regulated transcripts responded additively to dual ligand treatment. However, a significant fraction responded in a non-additive fashion. Several cytokines showing non-additive transcriptional responses to dual ligand treatment also showed non-additive protein production/secretion responses in separately performed experiments. Many of the genes with non-additive responses to LPS plus 2MA showed enhanced responses and encoded pro-inflammatory proteins. LPS plus $IFN{\gamma}$ appeared to induce both non-additive enhancement and non-additive attenuation of gene expression. The affected genes were associated with a variety of biological functions. These experiments reveal both dependent and independent regulatory pathways and point out the specific nature of the regulatory interactions.

Effects of Axial Ligand Basicity on the Isotropic NMR Shifts in Pyridine-Type Ligands Coordinated to the Paramagnetic Polyoxometalate, $[SiW_{11}Co^{11}O_{39}]^{6-}$

  • 김지영;박석민;소현수
    • Bulletin of the Korean Chemical Society
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    • 제18권4호
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    • pp.369-373
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    • 1997
  • When 1H NMR spectra of pyridine, 4-amino-, 4-methyl-, and 4-cyanopyridine coordinated to the paramagnetic polyoxometalate, [SiW11CoⅡO39]6- in D2O are compared, both α- and β-proton peaks are shifted upfield as the basicity of the ligand decreases. The isotropic shifts are separated into contact and pseudocontact contributions by assuming that the contact shifts are proportional to the isotropic shifts of the same ligands coordinated to [SiW11NiⅡO39]6-. This separation reveals that the shift variations with the axial ligand basicity are dominated by changes in the magnetic anisotropy (pseudocontact shift) of [SiW11CoⅡ(ptl)O39]6- (ptl=pyridine-type ligand). The magnitude of the magnetic anisotropy in a series of pyridine-type ligands increases linearly as the pKa of their conjugate acids decreases.

유기 음이온계 약물의 간수송과정에 있어서 대향수송현상에 관한 속도론적 연구 (Kinetic Analysis of the Counter-transport Phenomenon in the Hepatic Transport of Organic Anionic Drugs)

  • 정연복;한건;노정렬
    • Journal of Pharmaceutical Investigation
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    • 제22권4호
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    • pp.289-300
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    • 1992
  • The counter-transport phenomena in the hepatic transport of 1-anilino-8-naphthalene sulfonate (ANS) were kinetically investigated by analyzing the plasma disappearance-time profiles and the transport into the isolated hepatocytes. In vivo "counter transport phenomena" were simulated based on the perfusion model which incorporated the carrier-mediated transport and the saturable intracellular binding. The condition that the mobility of carrier-ligand complex is greater than that of free carrier is not essential for the occurrence of counter-transport phenomenon. To examine the inhibitory effects on the initial uptake of a ligand by the liver, it is necessary to judge whether the true counter-transport mechanism (trans-stimulation) is working or not. The initial plasma disappearance curves of ANS were then kinetically analyzed based on a two-compartment model, in which the ligand is eliminated only from the peripheral compartment (liver compartment). No effects on the initial plasma disappearance rates of ANS were observed after preloading of bromophenol blue (BPB) or rose bengal (RB) in the liver. Inhibitory effect of BPB or RB on the initial uptake (or efflux) rates of ANS by the isolated hepatocytes were not observed, suggesting that the true counter transport mechanism is not working. In conclusion, checking the preloading effects of transstimulation on the initial uptake of a ligand by the liver could be a useful criterion for carrier cycling and common use of the same carrier between two ligands. However, one cannot exclude those possibilities even if the preloading effects cannot be observed.

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Chromatographic Behavior of Proteins on Stationary Phase with Aminocarboxy Ligand

  • Li, Rong;Ju, Ming-Yang;Chen, Bin;Sun, Qing-Yuan;Chen, Guo-Liang;Shi, Mei;Wang, Xiao-Gang;Zheng, Jian-Bin
    • Bulletin of the Korean Chemical Society
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    • 제32권2호
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    • pp.590-594
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    • 2011
  • An aminocarboxy aspartic acid-bonded silica (Asp-Silica) stationary phase was synthesized using L-aspartic acid as ligand and silica gel as matrix. The standard protein mixtures were separated with prepared chromatographic column. The effects of solution pH, salt concentration and metal ion on the retention of proteins were examined, and also compared with traditional iminodiacetic acid-bonded silica (IDA-Silica) column. The results show that Asp-Silica column exhibited an excellent separation performance for proteins. The retention of proteins on Asp-Silica stationary phase was consistent with electrostatic characteristic of cation-exchange. The stationary phase displayed typical metal chelate property after fixing copper ion (II) on Asp-Silica. Under competitive eluting condition, protein mixtures were effectively isolated. Asp ligand showed better ion-exchange and metal chelating properties as compared with IDA ligand.