• Journal of the Korean Chemical Society
• /
• v.39 no.6
• /
• pp.446-452
• /
• 1995

Lithium intercalates, $Li_xFeMoO_4Cl$ ($1{\leq}X{\leq}2$) prepared by electrochemical lithiation of $FeMoO_4Cl$ crystallizes in monoclinic structure for all x values as revealed by x-ray diffraction and galvanostatic discharge experiments. According to the x-ray photoelectron spectroscopic study, Fe(III) is at first reduced to Fe(II) upon lithium intercalation with the x domain of $0{\leq}X{\leq}1$, where the crystal symmetry is changed from tetragonal to monoclinic. On the other hand, Mo(VI) is reduced to lower valent state upon further lithium intercalation ($1{\leq}X{\leq}2$), where no crystal symmetry transformation and reduction of Fe(II) to lower valent state are observed. The Mo 3d spectrum for $Li_2FeMoO_4Cl$ appears as a complex shape, but can be deconvoluted into the three sets of the doublet on the basis of Gaussian function, those which correspond to Mo(VI), Mo(V) and Mo(IV) states, respectively. The mixed valent states of molybdenum after further lithiation may be due to a competitive reaction between the formation of Mo(V) and its disproportionation to Mo(IV) and Mo(VI).

• Microbiology and Biotechnology Letters
• /
• v.40 no.3
• /
• pp.274-277
• /
• 2012

Cytokinesis is the final stage of cell division, dividing one mother cell into two daughter cells. For the cutting of a plasma membrane during bacterial cytokinesis, a tubulin homolog FtsZ protein is recruited from the cytoplasm to the division site. FtsZ protein polymerizes in a GTP-dependent manner and its N-terminal domain has a GTPase activity. In this study, we have begun to characterize FtsZ from Staphylococcus aureus (SA). Full-length SA FtsZ was cloned into pRSFDuet-1 vector and the clone was transformed into a BL21 (DE3) star cell. The recombinant SA FtsZ protein was purified using Ni-NTA affinity chromatography and dialysis. Using a spectrofluorometer, we showed that SA FtsZ undergoes a GTP-dependant polymerization in vitro. The polymer of the SA FtsZ protein disappeared after a few minutes, suggesting that the polymer is degraded as the GTP is consumed. This assay system may well be applied for inhibitor screening targeting S. aureus FtsZ.

• Applied Chemistry for Engineering
• /
• v.25 no.1
• /
• pp.14-19
• /
• 2014

Nanocomposites based on poly(methyl methacrylate) (PMMA)/poly(vinylidene fluoride) (PVDF) and poly(ethylene terephthalate) (PET)/(PVDF) blended with carbon fibers (CF) and carbon nanotube (CNT) were prepared by melt mixing in the twin screw extruder. Morphologies of the PMMA/PVDF/CF/CNT and PET/PVDF/CF/CNT nanocomposites were investigated using SEM. The aggregation of CNT was observed in PMMA/PVDF/CF/CNT nanocomposites while the good dispersion of CNT was shown in PET/PVDF/CF/CNT nanocomposites. In SEM image of PET/PVDF/CF/CNT nanocomposite, the CNT were mainly located at the PET domain of phase-separated PET/PVDF blend due to the ${\pi}-{\pi}$ interaction between the phenyl ring of PET and graphite sheet of the CNT's surface. In addition, a fairly good compatibility between PET/PVDF matrix and CF was shown in the SEM image. In the case of PET/PVDF nanocomposites blended with the co-addition of CF and CNT, the volume electrical resistivity decreased while no change was observed in PMMA/PVDF/CF/CNT composites. The degree of CNT dispersion in morphology results was consistent with the electrical conductivity results. From the DSC results, the crystallization temperature (Tc) of PET/PVDF/CF/CNT nanocomposites increased due to the co-addition of CF and CNTs acting as a nucleating agent. Flexural modulus of PET/PVDF/CF/CNT were sharply enhanced due to increasing the interaction between PET and CF.

• Applied Chemistry for Engineering
• /
• v.33 no.3
• /
• pp.309-314
• /
• 2022

Carbon dots (CDs) are few nanometer-sized carbon-based nanoparticles and emerging candidate materials in various fields such as biosensors and bioimaging due to their excellent optical properties and high biocompatibility. However, most CDs, emitting blue light, have limited their application in biomedical fields due to the low penetration of short-wavelength lights into the biological system. Therefore, there has been enormous need to develop long-wavelength emitting CDs. In this study, red-emitting CDs were successfully synthesized through the hydrothermal reaction of p-phenylenediamine with hydrochloric acid. In addition, the effect of the amount of hydrochloric acid on the formation of carbon dots, resulting in the variation of the chemical structures of CDs, were investigated, which was confirmed with the intensive structural analyses using infrared and X-ray photoelectron spectroscopy. It was found that the chemical structure of CDs governed their optical properties and quantum yield. Therefore, this study provides an insight into the role of acid in forming red-emitting CDs as the optimal probe for biomedical application.

• Biomolecules & Therapeutics
• /
• v.31 no.1
• /
• pp.127-138
• /
• 2023

Glycogen synthase kinase-3β (GSK-3β) is an important serine/threonine kinase that implicates in multiple cellular processes and links with the neurodegenerative diseases including Alzheimer's disease (AD). In this study, structure-based virtual screening was performed to search database for compounds targeting GSK-3β from Enamine's screening collection. Of the top-ranked compounds, 7 primary hits underwent a luminescent kinase assay and a cell assay using human neuroblastoma SH-SY5Y cells expressing Tau repeat domain (Tau_RD) with pro-aggregant mutation ΔK280. In the kinase assay for these 7 compounds, residual GSK-3β activities ranged from 36.1% to 90.0% were detected at the IC₅₀ of SB-216763. In the cell assay, only compounds VB-030 and VB-037 reduced Tau aggregation in SH-SY5Y cells expressing ΔK280 Tau_RD-DsRed folding reporter. In SH-SY5Y cells expressing ΔK280 Tau_RD, neither VB-030 nor VB-037 increased expression of GSK-3α Ser21 or GSK-3β Ser9. Among extracellular signal-regulated kinase (ERK), AKT serine/threonine kinase 1 (AKT), mitogen-activated protein kinase 14 (P38) and mitogenactivated protein kinase 8 (JNK) which modulate Tau phosphorylation, VB-037 attenuated active phosphorylation of P38 Thr180/ Tyr182, whereas VB-030 had no effect on the phosphorylation status of ERK, AKT, P38 or JNK. However, both VB-030 and VB-037 reduced endogenous Tau phosphorylation at Ser202, Thr231, Ser396 and Ser404 in neuronally differentiated SH-SY5Y expressing ΔK280 Tau_RD. In addition, VB-030 and VB-037 further improved neuronal survival and/or neurite length and branch in mouse hippocampal primary culture under Tau cytotoxicity. Overall, through inhibiting GSK-3β kinase activity and/or p-P38 (Thr180/Tyr182), both compounds may serve as promising candidates to reduce Tau aggregation/cytotoxicity for AD treatment.

• BMB Reports
• /
• v.50 no.12
• /
• pp.640-646
• /
• 2017

Regulatory B cells, also well-known as IL-10-producing B cells, play a role in the suppression of inflammatory responses. However, the epigenetic modulation of regulatory B cells is largely unknown. Recent studies showed that the bromodomain and extra-terminal domain (BET) protein inhibitor JQ1 controls the expression of various genes involving cell proliferation and cell cycle. However, the role of BET proteins on development of regulatory B cells is not reported. In this study, JQ1 potently suppressed IL-10 expression and secretion in murine splenic and peritoneal B cells. While bromodomain-containing protein 4 (BRD4) was associated with $NF-{\kappa}B$ on IL-10 promoter region by LPS stimulation, JQ1 interfered the interaction of BRD4 with $NF-{\kappa}B$ on IL-10 promoter. In summary, BRD4 is essential for toll like receptor 4 (TLR4)-mediated IL-10 expression, suggesting JQ1 could be a potential candidate in regulating IL-10-producing regulatory B cells in cancer.

• Korean Journal of Microbiology
• /
• v.47 no.2
• /
• pp.158-162
• /
• 2011

Amino acid sequence alignment shows that $\underline{P}$roteus $\underline{m}$irabilis $\underline{t}$ranscription $\underline{r}$egulator (PMTR) has cystein sequence homology at metal binding domain to CueR (copper resistance) protein, which conserves two cysteins (Cys 112 and Cys 120 in PMTR). Gel shift assay revealed that PMTR protein bound to promoter region of Escherichia coli copA (copper-translocating P-type ATPase) and Proteus mirabilis atpase (putative copper-translocating P-type ATPase) genes except that of E. coli zntA (zinc-translocating P-type ATPase) gene. DNase I protection experiment indicated that PMTR protein protected the region over -35 box and close to -10 box. DNase I hypersensitive bases were shown at C and A bases of labeled template strand and at G and C bases of labeled non-template strand of DNA. These hypersensitive bases were appeared in other metalloregulatory proteins of MerR family, which suggests protein-induced DNA bending.

• Polymer(Korea)
• /
• v.29 no.2
• /
• pp.166-171
• /
• 2005

EPDM (ethylene propylene diene monomer)/silicone rubber blends were prepared and the influence of a compatibilizer and thermal aging on the properties of the blends was investigated. The blends of which the compositions were varied in the range of 90/10 through $10/90\;wt\%$ were melt mixed by using a Brabender Plasticoder (internal mixer) and were vulcanized by a hot press. The morphology of the vulcanized EPDM/SR blends was examined by scanning electron microscopy (SEM). After the thermal Aging for 24, 48, 96 hrs at $100^{\circ}C$ in an air oven, hardness, tensile strength, elongation and contact angle of the blends were investigated. From the result of the morphology, it was confirmed that the domain size of the blends containing the compatibilizer was reduced. As the increase of the thermal aging time, hardness and tensile strength of the blends decreased but elongation and contact angle increased.

• Asian Journal of Atmospheric Environment
• /
• v.11 no.4
• /
• pp.330-343
• /
• 2017

Climate change is an important issue, with many researches examining not only future climatic conditions, but also the interaction of climate and air quality. In this study, a new version of the emissions processing software tool - Python-based PRocessing Operator for Climate and Emission Scenarios (PROCES) - was developed to support climate and atmospheric chemistry modeling studies. PROCES was designed to cover global and regional scale modeling domains, which correspond to GEOS-Chem and CMAQ/CAMx models, respectively. This tool comprises of one main system and two units of external software. One of the external software units for this processing system was developed using the GIS commercial program, which was used to create spatial allocation profiles as an auxiliary database. The SMOKE-Asia emissions modeling system was linked to the main system as an external software, to create model-ready emissions for regional scale air quality modeling. The main system was coded in Python version 2.7, which includes several functions allowing general emissions processing steps, such as emissions interpolation, spatial allocation and chemical speciation, to create model-ready emissions and auxiliary inputs of SMOKE-Asia, as well as user-friendly functions related to emissions analysis, such as verification and visualization. Due to its flexible software architecture, PROCES can be applied to any pregridded emission data, as well as regional inventories. The application results of our new tool for global and regional (East Asia) scale modeling domain under RCP scenario for the years 1995-2006, 2015-2025, and 2040-2055 was quantitatively in good agreement with the reference data of RCPs.

• Journal of Microbiology and Biotechnology
• /
• v.24 no.12
• /
• pp.1744-1754
• /
• 2014

The hepatitis C virus (HCV) RNA genome is replicated by an RNA replicase complex (RC) consisting of cellular proteins and viral nonstructural (NS) proteins, including NS5B, an RNA-dependent RNA polymerase (RdRp) and key enzyme for viral RNA genome replication. The HCV RC is known to be associated with an intracellular membrane structure, but the cellular components of the RC and their roles in the formation of the HCV RC have not been well characterized. In this study, we took a proteomic approach to identify stomatin, a member of the integral proteins of lipid rafts, as a cellular protein interacting with HCV NS5B. Co-immunoprecipitation and co-localization studies confirmed the interaction between stomatin and NS5B. We demonstrated that the subcellular fraction containing viral NS proteins and stomatin displays RdRp activity. Membrane flotation assays with the HCV genome replication-competent subcellular fraction revealed that the HCV RdRp and stomatin are associated with the lipid raft-like domain of membranous structures. Stomatin silencing by RNA interference led to the release of NS5B from the detergent-resistant membrane, thereby inhibiting HCV replication in both HCV subgenomic replicon-harboring cells and HCV-infected cells. Our results identify stomatin as a cellular protein that plays a role in the formation of an enzymatically active HCV RC on a detergent-resistant membrane structure.