• Bulletin of the Korean Chemical Society
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• v.19 no.11
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• pp.1198-1202
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• 1998

Aminolysis of aryl thiol-2-furoates and thiol-2-thiophenates with benzylainines are investigated in acetonitrile at 50.0 ℃. Relatively large selectivity parameters, ρx(βx), ρz(βx) and ρxz (> 0) together with the valid reactivity-selectivity principle are consistent with a stepwise acyl transfer mechanism with rate-limiting expulsion of the leaving group, thiophenolate anion, from the tetrahedral intermediate, T±. The first-order kinetics with respect to the benzylamine concentration and the relatively large secondary kinetic isotope effect involving deuterated benzylamine nucleophiles suggest a four-center type transition state in which concurrent leaving group departure and proton transfer are involved.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.197-197
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• 2011

In this study, in contrast with cases in which Scanning Tunneling Microscopy (STM) tip-induced reactions were instigated by the tunneling electrons, the local electric field, or the mechanical force between a tip and a surface, we found that the tungsten oxide (WO3) covered tungsten (W) tip of a STM acted as a chemical catalyst for the S-H dissociative adsorption of phenylthiol and 1-octanethiol onto a Ge(100) surface. By varying the distance between the tip and the surface, the degree of the tip-catalyzed adsorption could be controlled. We have found that the thiol head-group is the critical functional group for this catalysis and the catalytic material is the WO3 layer of the tip. After removing the WO3 layer by field emission treatment, the catalytic activity of the tip has been lost. 3-mercapto isobutyric acid is a chiral bi-functional molecule which has two functional groups, carboxylic acid group and thiol group, at each end. 3-Mercapto Isobutyric Acid adsorbs at Ge(100) surface only through carboxylic acid group at room temperature and this adsorption was enhanced by the tunneling electrons between a STM tip and the surface. Using this enhancement, it is possible to make thiol group-terminated surface where we desire. On the other hand, surprisingly, the WO3 covered W tip of STM was found to act as a chemical catalyst to catalyze the adsorption of 3-mercapto isobutyric acid through thiol group at Ge(100) surface. Using this catalysis, it is possible to make carboxylic acid group-terminated surface where we want. This functional group-selective adsorption of bi-functional molecule using the catalysis may be used in positive lithographic methods to produce semiconductor substrate which is terminated by desired functional groups.

• Polymer(Korea)
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• v.27 no.4
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• pp.330-339
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• 2003

Three kinds of macro-reticular bead-typed chelating resins having thiol groups were obtained from basic resins like poly(strene-co-divinylbenzene) (PSD) and poly(styrene-co-methyl methacrylate-co-divinylbenzene) (PSMD): the chelating resin (I) was prepared by chloromethylation of phenyl rings of PSD followed by thiolation using thiourea. The chelating resin (ll) was designed to provide enough space to chelate heavy metal ions; one chloromethyl group was obtained by chlorination of hydroxymethyl group provided by reduction of carboxylic ester group of PSMD and another chloromethyl group was obtained by direct chloromethylation of pendent phenyl group using chloromethyl methyl ether. Both of chloromethyl groups were thiolated by using thiourea. The chelating resin (III) was prepared by chlorosulfonation of phenyl rings of PSD followed by thiolation using sodium hydrosulfide. The adsorbtivity toward heavy metal ions was evaluated. The hydrophobic chelating resin (I) with thiol groups showed highly selective adsorption capacity f3r mercury ions. However, the chelating resin (II) with thiol groups showed mere effective adsorption capacity toward mercury ions than chelating resin (I) with thiol groups, and showed some adsorption capacity for other heavy metal ions like Cu$\^$2＋/, Pb$\^$2＋/, Cd$\^$2＋/ and Cr$\^$3＋/. On the other hand, the chelating resin (III) which have hydrophilic thiosulfonic acid groups was found to be effective adsorbents for some heavy metal ions such as Hg$\^$2＋/, Cu$\^$2＋/, Ni$\^$2＋/, Co$\^$2＋/, Cr$\^$3＋/ and especially Cd$\^$2＋/ and Pb$\^$2＋/.

• Journal of Embryo Transfer
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• v.12 no.3
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• pp.277-282
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• 1997

The purpose of this experiment was to determine the effects of thiol compounds, $\beta$-mercaptoethanol($\beta$-ME) and cystearrone with buffalo rat liver cell(BRLC) co-culture on the development and intracellular glutathione(GSH) concentrations of bovine embryos produced by in vitro inaturation(IVM) and in vitro fertilization(IVF). Bovine IVM /IVF embryos developed to 2~8 cell stage were co-cultured with BRLC in GRlaa with or without thiol compounds. The developmental rate beyond morulae stage in CRlaa containing 0, 10,25 and 50$\pi$M $\beta$-ME with BRLG were 63.0, 74.0, 72.3 and 77.1%, respectively. And the developmental rate with 0, 25, 50 and 75$\pi$M cystearnine with BRLC were 69.6, 77.6, 81.0 and 76.8%, respectively. The developmental rate beyond morulae stage of GRlaa containing thiol compound with BRLG group was higher than that of control group. The intracellular GSH concentrations of blastocysts cultured for 5 days in GRlaa containing 0 and 50$\pi$M $\beta$-ME or cysteamine with BRLG were 81.2 and 86.4, 83.2 and 84.2pM, respectively. The intracellular GSH concentrations of blastocysts in GRlaa containing thiol compounds with BRLG was slightly higher than that of control group The cell numbers of blastocysts were not difference in all experimental groups. These results indicate that thiol compounds with BRLG co-culture was increased the percentage of developed into morulae and blastocysts, and intracellular GSII concentrations of blastocysts embryos.

• Bulletin of the Korean Chemical Society
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• v.28 no.7
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• pp.1211-1214
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• 2007

• Food Science and Biotechnology
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• v.16 no.6
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• pp.1029-1034
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• 2007

Curcumin (diferuloyl methane), originated rhizomes of Curcuma longa L. has been suggested as an anti-inflammatory and anti-carcinogenic agent. In the present study, modulation of cytotoxic effects of curcumin on HeLa cells by different types of antioxidants was investigated. Cytotoxic effects of curcumin were significantly enhanced in the presence of superoxide dismutase (SOD) by decreasing $IC_{50}$ to 15.4 from $26.0\;{\mu}M$ after 24 hr incubation; the activity was not altered by catalase. The effect of curcumin was significantly less pronounced in the presence of 4 mM N-acetylcysteine (NAC). Low concentration (<1 mM) of NAC, however, increased the efficacy of curcumin. Cysteine and ${\beta}$-mercaptoethanol that have a thiol group, showed the similar biphasic patterns as NAC for modulating curcumin cytotoxicity, which was, however, constantly enhanced by ascorbic acid, a non-thiol antioxidant. In the presence of SOD, ascorbic acid, and 0.5 mM NAC, cellular levels of curcumin were significantly increased by 31-66%, whereas 4 mM NAC decreased the level. The present results indicate that thiol reducing agents showed a biphasic effect in modulating cytotoxicity of curcumin; it is likely that their thiol group is reactive with curcumin especially at high concentrations.

• Applied Biological Chemistry
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• v.40 no.3
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• pp.243-248
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• 1997

In order to evaluate the usefulness of O. javanica for the phytoremediation, it was grown for 1, 3, 7, 14, 21 days and was exposed to $50\;{\mu}M\;of\;CdCl_2$ in hydroponic medium after 3 weeks. Its biomass and contents of chlorophylls were analyzed. The growth of O. javanica showed little difference between cadmium treated and non-treated groups, while its contents of chlorophylls of Cd-treated group decreased up to 50% compared to the case of non-treated group. Its accumulated cadmium concentrations were 2.1, 7.3 and $113\;{\mu}moles\;Cd/g$ dry weight in the leaf, stem and root, respectively. The total contents of thiol increased 0.5, 1 and 7 times in the leaf, stem and root, respectively, while the contents of glutathione tended to decrease by 43%, 70% and 47% in the leaf, stem and root, respectively. Using HPLC analysis, the reasonable peaks of thiol compounds in shoot and root of Cd-treated sample were compared to those of non-treated sample in O. javanica, and found to be phytochelatins. In case of Nicotiana tabacum cv. Xanthi tested as control plant, the cadmium treatment for 3 weeks resulted in the decrease of both biomass and chlorophyll up to 70% and 75%, respectively. The roots of tobacco became rotten and eventually died. These results suggested that Oenanthe javanica is cadmium-tolerant hyperaccumulator.(Received December 20, 1996; accepted March 17, 1997)

• Journal of Life Science
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• v.7 no.3
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• pp.228-233
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• 1997

A thiol protease has been isolated and partially purified from encysted brine shrimp Artemia franciscana using a four-step procedure(filtration, salting out, gel filtration and ion exchange chromatography). The optimum pH of the enzyme for caseinolytic activity was appeared to be 3.0, and the enzymematic activity was stable up to pH 6.0 but lost completely at the pH higher than 8.0. The optimal temperature of the enzyme was appeared to be 35$^{\circ}$C, and ninety percent of the enzyme activity was lost at 45$^{\circ}$C. Various metal ions, e.g., zinc, copper, iron, inhibited the enzyme activity; however, heavy metal chelator, e.g., EDTA, stimulated the enzyme activity. The protease was concluded to be a member of the thiol group protease, since it was inhibited by thiol protease inhibitors and iodoacetate. The protease was also concluded to be a acid protease based on optimum pH.

• Journal of Environmental Health Sciences
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• v.11 no.2
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• pp.65-75
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• 1985

Microorganisms capable of utilizing diaminododecane containing amine groups diterminally were isolated from the soil by enrichment culture. One strain of these isolated strain, designated as EL-0112L, was selected for this study. The results of this study were as follows. 1. This isolated strain EL-0112L was identified as Microbacterium, from the results of morphological, cultural, and biochemical tests. This isolated strain was named temporarily Microbacterium sp. EL-0112L for convenience. 2. Microbacterium sp. EL-0112L was tested for ability to utilize different kinds of substitued alkanes containing cyan, amine, chloro, and thiol groups(monoterminally or diterminall substituted) as carbon source. Pentamethylenediamine, hexamethylenediamine, n-decane, laurylamine, and alkane derivatives containing cyan, chloro, and thiol groups were not utilized by Microbacterium sp. EL-0112L. 3. The alkane derivatives that did not serve as growth substrates were tested further in oxidation tests using resting cell preparation of Microbacterium sp. EL-0112 L. Alkane derivatives containing cyan, chloro, thiol groups, and n-decane were oxidized by Microbacterium sp. EL-0112 L. It is possible that this isolated strain is also able to degrade their substituted counterparts since they are structually similar to diaminododecane. The remarkable substrates that were being oxidized were dichlorodecane, and 1-dodecanethiol. Microbacterium sp. EL- 0112L could not oxidize pentamethylenediamine, and hexamethylenediamine. 4. The metabolic products formed from diaminododecane by Microbacterium sp. EL-0112 L were acid compound containing carboxyl group and not containing amine group. On the thin layer chromatography, Rf values of these metabolic products were different from that of the product formed by Corynebacterium sp. EL-0112L. These results suggested the specificity of diaminododecane as carbon source.

• Journal of Photoscience
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• v.4 no.3
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• pp.133-140
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• 1997

A system for studying oxidative hemolysis has been used by controling UV-irradiation and concentration of a novel molecular probe, N,N'-bis(2-hydroperoxy-2-methoxyethyl)-1,4,5,8-naphthalenetetra-carboxylic diimide (NP-III), which generates hydroxyl radical upon longer wavelength photoirradiation (> 350 nm). NP-III induces 25~30% of hemolysis at low concentration (50 $\mu$M) for 3h-irradiation of UVA. The simultaneous treatment of N-ethylmaleimide (NEM) with NP-IH completely hemotyzed erythrocytes under the same conditions as NP-III alone by both decreasing thiol group and increasing lipid peroxidation in erythrocyte membrane. However. thiol-reducing agents prevented the protein-crosslinking and lipid peroxidation on the NEM-synergistic hemolysis by partially scavenging hydroxyl radical and maintaining the thiol group of erythrocyte membrane in the reduced state. In addition, erythrocytes pretreated with 2,2,5,7,8-pentamethyl-6-hydroxychromane (PMC), vitamin E homologue was able to delay and decrease the lipid peroxidation when compared to cells pretreated with both NEM and PMC. We suggest that the presence of reduced thiols in inner membrane protein by GSH can prevent the protein-crosslinking and the lipid peroxidation, and eventually prevent the oxidative hemolysis of erythrocyte.