• 약학회지
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• 제38권6호
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• pp.664-672
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• 1994

Eighteen new hybrid bivalent ligand quinolones that contain two different type of pharmacophores in a single molecule were prepared and evaluated for in viかo antibacterial activity. Hybrid bivalent ligands p-nitrobenzyloxycarbonyl quinolones were prepared by the treatment of active esters of succinyl fluoroquinolones with 1,7-disubstituted fluoroquinolone carboxylic acids in DMF. Eighteen final quinolone carboxylic acids were obtained by the reduction of compounds $25{\sim}42$ with hydrogen in the presence of 10% Pd-C. Among these derivatives, compound[56] showed the most potent antibacterial activity against a wide range of microoranisms.

• 대한화학회지
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• 제60권6호
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• pp.402-409
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• 2016

3-Mecaptopropionic acid (MPA) 리간드와 하이브리드 타입 리간드($MPA+CdCl_2$)로 각각 부동화(passivation) 된 2.8 nm 크기의 황화납 콜로이드 양자점 박막을 제작하고, 각각을 대기 중, 질소 분위기에서 열처리, 오존 처리 하였을 때 나타나는 두 양자점 박막의 전자 구조와 조성 원소의 변화를 광전자 분광법을 이용하여 연구하였다. 대기에서 열처리는 리간드 종류와 관계없이 황화납 양자점의 가전자대 시작점이 공통적으로 약한 p-도핑 효과가 있음을 직접적으로 확인할 수 있었다. 또한, 오존처리 후 두 황화납 양자점 표면에 공통적으로 $Pb(OH)_2$, $PbSO_x$, PbO를 형성하는 것을 확인하였다. 하지만, 오존에 의해 형성된 산화물 중 PbO 성분은 특별히 하이브리드 타입 리간드로 부동화 된 양자점에서 형성된 양이 MPA 리간드만으로 부동화 된 양자점과 비교했을 때 감소한 것을 확인할 수 있었다. 이것은 PbS(111) 격자면에 있는 과량의 Pb 표면이 $Cl_2$으로 부동화되면서, Pb 양이온과 오존의 반응을 차단함으로써 PbO의 형성을 어렵게 했기 때문으로 추정된다.

• 한국환경성돌연변이발암원학회지
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• 제22권3호
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• pp.175-182
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• 2002

Endocrine disruptors (EDs) are the chemicals that affect endocrine systems through activation or inhibition of steroid hormone response. It is necessary to have a good system to evaluate rapidly and accurately endocrine-disrupting activities of suspected chemicals and their degradation products. The key targets of EDs are nuclear hormone receptors, which bind to steroid hormones and regulate their gene transcription. We constructed a co-expression system of Gal4p DNA binding domain (DBD)- ligand binding domain of human estrogen receptor $\alpha$ or $\beta$, and Gal4p transactivation domain (TAD)-co-activator AIB-1, SRC-1 or TIF-2 in Saccharomyces cerevisiae with a chromosome-integrated lacZ reporter gene under the control of CYC1 promoter and Gal4p binding site (GAL4 upstream activating sequence, GAL4$_{UAS}$). Expression of this reporter gene was dependent on the presence of estrogen or EDs in the culture medium. We found that the two-hybrid system with combination of the hER$\beta$ LBD and co-activator SRC-1 was most effective in the xenoestrogen-dependent induction of reporter activity. The extent of transcriptional activation by those chemicals correlated with their estrogenic activities measured by other assay systems, indicating that this assay system is efficient and reliable for measuring estrogenic activity. The data in this research demonstrated that the yeast detection system using steroid hormone receptor and co-activator is a useful tool for identifying chemicals that interact with steroid receptors.s.

• Animal cells and systems
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• 제13권1호
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• pp.1-8
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• 2009

Toll-like receptor (TLR) family proteins, type I transmembrane proteins, play a central role in human innate immune response by recognizing common structural patterns in diverse molecules from bacteria, viruses and fungi. Recently four structures of the TLR and ligand complexes have been determined by high resolution x-ray crystallographic technique. In this review we summarize reported structures of TLRs and their proposed activation mechanisms. The structures demonstrate that binding of agonistic ligands to the extracellular domains of TLRs induces homo- or heterodimerization of the receptors. Dimerization of the TLR extracellular domains brings their two C-termini into close proximity. This suggests a plausible mechanism of TLR activation: ligand induces dimerization of the extracellular domains, which enforces juxtaposition of intracellular signaling domains for recruitment of intracellular adaptor proteins for signal initiation.

• 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.

• Parasites, Hosts and Diseases
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• 제46권4호
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• pp.209-216
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• 2008

A monoclonal antibody against Toxoplasma gondii of Tg556 clone (Tg556) blotted a 29 kDa protein, which was localized in the dense granules of tachyzoites and secreted into the parasitophorous vacuolar membrane (PVM) after infection to host cells. A cDNA fragment encoding the protein was obtained by screening a T. gondii cDNA expression library with Tg556, and the full-length was completed by 5'-RACE of 2,086 bp containing an open reading frame (ORF) of 669 bp. The ORF encoded a polypeptide of 222 amino acids homologous to the revised GRA3 but not to the first reported one. The polypeptide has 3 hydrophobic moieties of an N-terminal stop transfer sequence and 2 transmembrane domains (TMD) in posterior half of the sequence, a cytoplasmic localization motif after the second TMD and an endoplasmic reticulum (ER) retrival motif in the C-terminal end, which suggests GRA3 as a type III transmembrane protein. With the ORF of GRA3, yeast two-hybrid assay was performed in HeLa cDNA expression library, which resulted in the interaction of GRA3 with calcium modulating ligand (CAMLG), a type II transmembrane protein of ER. The specific binding of GRA3 and CAMLG was confirmed by glutathione S-transferase (GST) pull-down and immunoprecipitation assays. The localities of fluorescence transfectionally expressed from GRA3 and CAMLG plasmids were overlapped completely in HeLa cell cytoplasm. In immunofluorescence assay, GRA3 and CAMLG were shown to be co-localized in the PVM of host cells. Structural binding of PVM-inserted GRA3 to CAMLG of ER suggested the receptor-ligand of ER recruitment to PVM during the parasitism of T. gondii.

• BMB Reports
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• 제32권3호
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• pp.279-287
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• 1999

The aromatic hydrocarbon receptor (AhR) is a cytosolic protein that binds the environmental pollutant, dioxin. The liganded AhR translocates into the nucleus where it heterimerizes with a constitutive nuclear protein, AhR nuclear translocator (Arnt). The N-terminal regions of both AhR and Arnt contain basic helix-loop-helix (bHLH) and Per-AhR-Arnt-Sim (PAS) motifs that are required for DNA binding, dimerization, and ligand binding whereas the C-terminal regions of both AhR and Arnt contain transactivation domains. Here, results from the mammalian two-hybrid system indicate that Arnt can make a homodimer but AhR cannot. In the presence of dioxin, the interaction between AhR and Arnt is stronger than that of the Arnt homodimer, suggesting that Arnt prefers to make a heterodimer with the liganded AhR rather than a homodimer. Transfection analyses using the GAL4-driven reporter system suggest that AhR's N-terminal region represses its own transactivation domain, as well as exogenous transactivation domains such as Sp 1 and VP16. Interestingly, the repressed transactivation domains of AhR are activated by ligand-dependent heterodimerization with Arnt. These observations suggest that heterodimerzation with Arnt is necessary not only for DNA binding but also for activation of the repressed transactivation capability of AhR.

• Biomolecules & Therapeutics
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• 제6권4호
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• pp.337-344
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• 1998

The objective of the present study was to investigate the effect of senescence on the binding properties of muscarinic receptors in the neostriatum of young (3 months), middle-aged (18 months) and aged (33 months) male Fischer 344 x Brown Norway hybrid rats by employing direct binding of selective radiolabeled antagonists. Using the selective M, muscarinic receptor antagonist, $[^3H]$AF-DX384, as the ligand, no significant difference in the maximal receptor density (Bmax) was observed in the neostriatum among any age-groups. In contrast, with the selective M, receptor antagonist, $[^3H]$4-DAMP, a significant increase in the number of muscarinic receptors was observed in neostriatal membrane fractions prepared from the aged animals relative to that observed in the young rats. For each ligand there was no age-related change in its affinity (Kd) for the muscarinic receptors. These results indicate that the observed age-related changes in the muscarinic receptor density may not be necessarily decremuntal and depend upon the muscarinic receptor subtype examined.

• Elastomers and Composites
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• 제48권1호
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• pp.61-66
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• 2013

일반식을 $[N(CH_3)(CH_2)_2(Bm-R)_2]CrCl_3$ [여기에서 Bm = benzimidazolyl, R = H (3a); -Me(3b); -Bn(3c)]으로 나타낼 수 있는 일련의 세 다리 dibenzimidazolyl 리간드를 갖는 크롬(III) 착물을 합성, 메틸알루미녹산으로 활성화시켜 이를 부타디엔의 입체규칙성 중합을 통해 trans-1,4-polybutadiene을 제조하였다. 크롬 착물의 부타디엔 중합 활성은 리간드의 구조에 따라 달라졌으며, 활성은 3a > 3c > 3b 순으로 낮아졌다. 모든 착물을 이용하여 제조된 폴리부타디엔의 미세구조를 조사한 결과 거의 완벽한 trans-1,4 구조를 보였으며, 분자량도 비교적 높게 나타났다.

• 상하수도학회지
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• 제20권6호
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• pp.893-904
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• 2006

To improve sensitivity of biosensor as yeast two-hybrid detection system for estrogenic activity of suspected chemicals, we tested effects of several combinations of the bait and fish components in the two-hybrid system on Saccharomyces cerevisiae inducted a chromosome-integrated lacZ reporter gene that was under the control of CYC1 promoter and the upstream Gal4p-binding element $UAS_{GAL}$. The bait components that were fused with the Gal4p DNA binding domain are full-length human estrogen receptor ${\alpha}$ and its ligand-binding domain. The fish components that were fused with the Gal4p transcriptional activation domain were nuclear receptor-binding domains of co-activators SRC1 and TIF2. We found that the combination of the full-length human estrogen receptor ${\alpha}$ with the nuclear receptor-binding domain of co-activator SRC1 was most effective for the estrogen-dependent induction of reporter activity among the two-hybrid systems so far reported. The relative strength of transcriptional activation by representative natural and xenobiotic chemicals was well correlated with their estrogenic potency that had been reported with other assay systems.