• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.122-126
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• 2008

The magnetic properties of the organic/inorganic hybrid copper-methylenediphosphonate, Cu2(O3PCH2PO3) were examined by performing the spin dimer analysis based on the extended Hckel tight binding method. In Cu2(O3PCH2PO3) the CuO3 chains made up of edge-sharing CuO5 square pyramidal units are inter-linked by O-P-O bridges. The Cu-O-Cu superexchange interactions of the CuO3 chains are negligibly weak compared with the Cu-O…O-Cu super-superexchange interactions that occur between the CuO3 chains. The spin exchange interactions of Cu2(O3PCH2PO3) are dominated by three super-superexchange interactions, which leads to a three-dimensional antiferromagnetic spin lattice. The strongest spin exchange interactions form isolated spin dimers, which suggests that, to a first approximation, the magnetic properties can be described in terms of an isolated spin dimer model.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3577-3585
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• 2013

Syndecan-4 (heparan sulfate proteoglycan), biologically important in cell-to-cell interactions and tumor suppression, was studied through mutation of the GXXXG motif of its transmembrane domain (Syd4-TM), a motif which governs dimerization. The expression and purification of the mutant (mSyd4-TM) were optimized here to assess the function of the GXXXG motif in the dimerization of Syd4-TM. mSyd4-TM was obtained in M9 minimal media and its oligomerization was identified by SDS PAGE, Circular Dichroism (CD) spectroscopy, mass spectrometry and NMR spectroscopy. The mutant, unlike Syd4-TM, did not form dimers and was observed as monomers. The GXXXG motif of Syd-4TM was shown to be an important structural determinant of its dimerization.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2193-2198
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• 2011

We prepared polycatenar 1H-imidazole amphiphiles having a structure in which a 1H-imidazole head was connected through a benzene ring to a pheny group having two or three oligo(ethylene glycol) chains and studied their supramolecular assembly by fluorescence spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM). When the aqueous solutions of the amphiphiles ($5{\times}10^{-5}M{\sim}10^{-3}M$) were deposited onto a carbon-coated copper grid and dried, twisted structures with diameters of ~200-300 nm were imaged by TEM and AFM. We presume that the structures comprised a chain of the amphiphile dimers formed via successive hydrogen bonding between the 1H of the imidazole group and 3N of the neighboring one. In a solution of pH 4, entangled fibers with diameters of several nanometers were observed by TEM. In a pH 10 solution, film-like aggregates formed exclusively. The 1H-imidazole amphiphiles hydrolyzed tetraethoxysilane to induce gelation to form fibrous and spherical silica structures at neutral pH in aqueous solutions. No silica was formed when imidazole was used instead of the amphiphiles, suggesting that the selfassembled aggregates of the amphiphiles were responsible for the gelation.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.220-222
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• 2005

We can classify two cases in a way to observe an atom of gas state or a molecule using the laser. First case is way to use dispersion phenomenon like Rayleigh scattering, Thomson scattering, Mie scattering, Raman Scattering. And Second case is a way to use change phenomenon like a LAS (Laser Absorption Spectroscopy), LIF (Laser Induced Fluorescent). In this paper, we have measured the meta-stable density and the distribution by using a LAS method in Xe discharge lamp. The laser absorption spectroscopy (LAS) is useful to investigate the behavior of such species. The xenon atoms in the $1S_4$ and $1S_5$ generate excited $Xe^*$(147nm) and $Xe_{2}^*$(173nm) dimers in Xe plasma. It is found that the intensity of VUV 147nm emission is proportional to that of the IR 828nm emission, and the VUV 173nm emission is roughly proportional to that of the IR 823nm emission. The laser is used CW laser that consist of AlGaAs semiconductor and energy level is used 823.16nm wavelength. We measured signal of monochrometer from the lamp center while will change a discharge electric current by 6mA in 3mA and calculated meta-stable state density of a xenon atom through a measured value.

• BMB Reports
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• v.42 no.3
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• pp.160-165
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• 2009

The temperate Staphylococcus aureus phage ${\Phi}11$ harbors cI and cro repressor genes similar to those of lambdoid phages. Using extremely pure ${\Phi}11$ Cro (the product of the ${\Phi}11$ cro gene) we demonstrated that this protein possesses a single domain structure, forms dimers in solution at micromolar concentrations and maintains a largely $\alpha$-helical structure even at $45^{\circ}C$. ${\Phi}11$ Cro was sensitive to thermolysin at temperatures ranging from $55-75^{\circ}C$ and began to aggregate at ${\sim}63^{\circ}C$, suggesting that the protein is moderately thermostable. Of the three homologous 15-bp operators (O1, O2, and O3) in the ${\Phi}11$ cI-cro intergenic region, ${\Phi}11$ Cro only binds efficiently to O3, which is located upstream of the cI gene. Our comparative analyses indicate that the DNA binding capacity, secondary structure and dimerization efficiency of thermostable ${\Phi}11$ Cro are distinct from those of P22 Cro and $\lambda$ Cro, the best characterized representatives of the two structurally different Cro families.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.2
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• pp.134-139
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• 2006

Methanotrophs are microorganisms that possess the unique ability to utilize methane as their sole source of carbon and energy. A novel culture system, known as the compulsory circulation diffusion system, was developed for rapid growth of methanotrophic bacteria. Methanol dehydrogenase (MDH, EC 1.1.99.8) from Methylomicrobium sp. HG-1, which belongs to the type I group of methanotrophic bacteria, can catalyze the oxidation of methanol directly into formaldehyde. This enzyme was purified 8-fold to electrophoretic homogeneity by means of a 4 step procedure and was found in the soluble fraction. The relative molecular weight of the native enzyme was estimated by gel filtration to be 120 kDa. The enzyme consisted of two identical dimers which, in turn, consisted of large and small subunits in an ${\alpha}_2{\beta}_2$ conformation. The isoelectric point was 5.4. The enzymatic activity of purified MDH was optimum at pH 9.0 and $60^{\circ}C$, and remained stable at that temperature for 20 min. MDH was able to oxidize primary alcohols from methanol to octanol and formaldehyde.

• Herbal Formula Science
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• v.19 no.2
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• pp.93-108
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• 2011

Objectives : Angelica sinensis has been used extensively in Korean traditional medicine. Although thorough clinical trials are lacking, Various pharmacological actions for Angelica sinensis has been identified newly using animal models. In addition, it was reported that reactive intermediates, potentially causing toxic effects, was isolated from components in Angelica sinensis. In this article, it was purposed for explanation and introduction of new studies for Angelica sinensis. in terms of Pharmacological action and Toxicity. Methods : New studies for Angelica sinensis were reviewed and summarized in terms of pharmacological action and toxicity. Results and Conclusions : Angelica sinensis and its components including phthalide, phthalide dimers, polysaccharides, polyacetylenes, ligustilide와 butylidenephthalide as well as organic acid showed a variety of pharmacological actions on uterine, cardiovascular system and immune system. In addition, it was identified that three components of such as ligustilide, caffeic acid and safrole was biotransformed to reactive intermediates causing possibly toxicity.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1995.04a
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• pp.80-80
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• 1995

T4 Endonuclease V (Mw 16,000) acts as a repair enzyme for UV induced pyrimidine dimers in DNA. Many researchers have studied the biochemical characteristics of the enzyme. However the precise action mechanism of T4 endo V has not fully elucidated yet. In our laboratory NMR spectroscopy technique is being used for the structural study of T4 endo V. Because of its low temperature stability and high content of ${\alpha}$-helix, the conventional $^1$H NMR technique was inapplicable. Therefore we utilized stable isotope labeling technique and so far prepared about 10 amino acid specific labeled proteins. The HSQC spectra of amino acid specific labeled proteins will help us to interpret the triple resonance 3D, 4D data which are under processing, We also studied the behaviors of specific amino acid residues whose roles might be critical. When the enzyme labeled by $\^$15/N-Thr was mixed with the substrate oligonucleotide (semispecific -TT- sequence), one crosspeak in its HSQC spectrum was completely desappeared, which means that one of seven Thr residues is in the binding site of the enzyme with DNA, This result is well consistent with previous report that implicated the Thr 2 residue in the activity of the enzyme. Similar studies were carried on the behaviors of Arg and Tyr residues.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.132-132
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• 2012

Depositing $CaF_2$[0.6% lattice-mismatch] on the Si(001)-$4^{\circ}$ off surface [composed of a single (001) domain with regularly-arrayed double-layer DB steps and located between (1 1 19) and (1 1 21)] held at $700^{\circ}C$, $CaF_2$ molecules are preferentially adsorbed on the dimers and dissociated to Ca and F atoms. Dissociated Ca atoms form a silicide layer of a $2{\times}3$ structure on the (001) terrace, while F atoms are desorbed from the surface. Once the terrace is covered with a calcium silicide layer, CaF starts to be adsorbed selectively on the steps, as shown in Fig. (a). With $CaF_2$ deposition exceeding 1 ML, the (1 1 17) surface having 1-D $CaF_2$ nanodots are formed as shown in Fig. (b). By the present STM study, it has been clearly disclosed that the calcium silicide interfacial layer is preformed prior to adsorption of $CaF_2$ on vicinal Si(001) surface.

• Journal of Microbiology and Biotechnology
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• v.15 no.3
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• pp.484-490
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• 2005

Human ribosomal protein S3 (rpS3), which has a DNA repair endonuclease activity, is a multifunctional protein. This protein is involved in DNA repair, translation, and apoptosis. In particular, rpS3 has a lyase activity, which cleaves the phosphodiester bond of damaged sites such as cyclobutane pyrimidine dimers and AP sites. Here, using deletion analysis, we identified that the repair endonuclease domain resides in the C-terminal region (165-243 aa) of rpS3. We also found that ectopic expression of GST-rpS3 in bacterial strain BL21 promoted the resistance of these cells to ultraviolet (UV) radiation and hydrogen peroxide ($H_{2}O_{2}$) treatment. The repair domain of rpS3 was sufficient to exhibit the resistance to UV irradiation and recover cell growth and viability, showing that the repair activity of rpS3 is responsible for the resistance to UV irradiation. Our study suggests that rpS3 is able to process DNA damage in bacteria via its repair domain, showing the resistance to genotoxic stress. This implies that rpS3-like activity could be operative in bacteria.