• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2433-2442
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• 2011

The three dimensional quantitative structure activity relationship (3D QSAR) models were developed using Comparative molecular field analysis (CoMFA), comparative molecular similarity indices analysis (CoMSIA) and docking studies. The fit of Quinazolinone antifolates inside the active site of modeled bovine dihydrofolate reductase (DHFR) was assessed. Both ligand based (LB) and receptor based (RB) QSAR models were generated, these models showed good internal and external statistical reliability that is evident from the $q^2_{loo}$, $r^2_{ncv}$ and $r^2_{pred}$. The identified key features enabled us to design new Quinazolinone analogues as DHFR inhibitors. This study is a building bridge between docking studies of homology modeled bovine DHFR protein as well as ligand and target based 3D QSAR techniques of CoMFA and CoMSIA approaches.

• Journal of the Korean Applied Science and Technology
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• v.26 no.3
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• pp.370-378
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• 2009

Kinetic studies on the ligand substitution reactions of cyanocomplexes were performed in several micellar solutions. It showed the observed rate constants was found to be independent of the entering ligand concentration at high concentration of cyanopyridine and pyrazinecarboxylate. We could see also that in nonionic and anionic micellar solutions no influence of changes in the surfactant concentration on the observed rate constants was found. Taking into account the hydrophilic nature of the cobalt complex, the cobalt complex molecule was expected to be located in the aqueous phase of the micellar systems, where the reaction would take place. In cationic micellar solutions, a small increase in the observed rate constant was found when the cationic surfactant concentration increased. After reaching a maximum, the rate constant decreased on increasing surfactant concentration and subsequently it reached a plateau, where the observed rate constant was independent of changes in the surfactant concentration.

• CELLMED
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• v.3 no.1
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• pp.3.1-3.3
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• 2013

The receptor activator of NF-${\kappa}B$ ligand (RANKL), a member of the tumor necrosis factor ligand family, has extensive functions beyond osteoclast development. RANKL is expressed in many immune cells such as osteoblasts, osteocytes, marrow stromal cells, activated T cells, synovial cells, keratinocytes, and mammary gland epithelial cells as well as in various tissues. The ligation of RANK by RANKL promotes dendritic cells (DCs) survival through prosurvival signals and the up-regulation of the anti-apoptotic proteins Bcl-2 and Bcl-$x_L$ and plays a crucial role in DCs-mediated Th1 differentiation. Therefore, RANKL plays an important role in the regulation of DCs/T cells-mediated specific immunity. This review will briefly inform our current understanding of the role of RANKL signaling in T cells-DCs communication in the immune system.

• Journal of the Korean Chemical Society
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• v.22 no.3
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• pp.133-137
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• 1978

A straight chain flexible tetraamine ligand, 1,l0-dipropyl-5R-methyltriethylenetetraamine(R-$Pr_2$metrien) has been synthesized, and the dichloro and dinitro cobalt(III) complexes of this ligand have been prepared. The ligand has been expected to show a topological preference for the trans isomer. As expected, only trans geometrical isomers have been obtained and their structures have been elucidated via elemental analyses, nmr, electronic absorption and CD data.

• Journal of the Korean Chemical Society
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• v.22 no.2
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• pp.99-104
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• 1978

The synthesis of a bidentate secondary amine ligand, 2,2-bis(methylaminomethyl-2,3-dioxolane(methylaminomethyl)-1,3-dioxolane(mexo) and the preparation of dichloro and trans-R-cyclohexanediamine platinum(II) complexes of this ligand are reported. The structures of the ligand and complexes prepared have been elucidated via elemental analyses, nmr, electronic absorption, and CD spectra.

• IMMUNE NETWORK
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• v.15 no.3
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• pp.121-124
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• 2015

Now, it has been being accepted that reverse signaling through CD137 ligand (CD137L) plays an important role in vivo during hematopoiesis and in immune regulation. However, due to technical difficulty in dissecting both directional signaling events simultaneously in vivo, most biological activities caused by CD137-CD137L interactions are considered as results from signaling events of the CD137 receptor. To make the story more complex, $CD137^{-/-}$ and $CD137L^{-/-}$ mice have increased or decreased immune responses in a context-dependent manner. In this Mini review, I will try to provide a plausible explanation for how CD137L signaling is controlled during immune responses.

• Journal of the Korean Magnetic Resonance Society
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• v.5 no.2
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• pp.130-137
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• 2001

Backbone dynamics of the catalytic residues in free and steroid-bound $\Delta$$^{5}$ -3- ketosteroid isomerase from Pseudomonas testosteroni has been examined by $^{15}$ N relaxation measurements. The relaxation data were analyzed using the model-free formalism to extract the model-free parameters (S$^2$, $\tau$$_{e}$, and R$_{ex}$). Tyr-34 and Asp-99 exhibit enhanced high-frequency (pico- to nanosecond) internal motions in the free enzyme, which are restricted upon ligand binding, while Asp-38 experiences severe restriction of the internal motions in the fee enzyme, suggesting that Tyr-14 and Asp-99 are more actively involved in the ligand binding than Asp-38. The results also indicate that the H-bond network in the catalytic cavity might be slightly strengthened upon ligand binding, which may have some implications on the enzyme mechanism.he enzyme mechanism.m.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.367-370
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• 2015

Monolayer transition metal dicalcogenide (TMDC) materials are currently attracting extensive attention due to their distinctive electronic, transport, and optical properties. For example, monolayer $MoS_2$ exhibits a direct band gap in the visible frequency range, which makes it an attractive candidate for the photocatalytic water splitting. For the photoelectrochemical water splitting, the appropriate band edge positions that overlap with the water redox potential are necessary. Similarly, appropriate band level alignments will be crucial for the light emitting diode and photovoltaic applications utlizing heterojunctions between two TMDC materials. Carrying out first-principles calculations, we here investigate how the band edges of $MoS_2$ can be adjusted by surface ligand functionalization. This study will provide useful information for the realization of ligand-based band engineering of monolayer $MoS_2$ for various electronic, energy, and bio device applications.

• YAKHAK HOEJI
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• v.60 no.2
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• pp.78-84
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• 2016

N-Phenylthiourea derivatives and catechol oxidase receptor complex was studied using molecular mechanics method. The starting structure was adopted from the protein databank and the calculation of energy minimization and molecular dynamics was performed with AMBER package. The molecular dynamics showed that the simulation time span of 20 ns was long enough to observe the interaction profile and stationary ligand-receptor configuration in the complex. The conformation of the ligand was related to the interaction to the receptor and the efficacy was also interpreted in this context.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.829-834
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• 2010

Ligand variation was carried out on a cobalt(III) complex of Salen-type ligand comprised of 1,2-cyclohexenediamine and salicylaldehyde bearing a methyl substituent on 3-position and -[$CMe(CH_2CH_2CH_2N^+Bu_3)_2$] on 5-position, which is a highly active catalyst for $CO_2$/propylene oxide copolymerization. Replacement of the methyl substituent with bulky isopropyl group resulted in alteration of the binding mode, consequently lowering turnover frequency significantly. Replacement with an ethyl group preserved binding mode and activity. Replacement of the tributylammonium unit with trihexylammonium or trioctylammonium, or replacement of 1,2-cyclohexenediamino unit with -$NC(Me)_2CH_2N$- decreased activity, even though the binding mode was unaltered.