• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.243-243
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• 2012

Self-assembled monolayers (SAMs) prepared by aromatic thiols on gold surfaces have much larger potential for electronic device applications due to their electronic properties. In this study, the formation and structures of SAMs prepared by benzenethiol (BT), toluenethiol (TT), 2-fluorobenzenethiol (2-FBT), 3-fluorobenzenethiol (3-FBT), 4-fluorobenzenethiol (4-FBT), 4-chlorobenzenethiol (4-CBT), 4-fluorobenzenemethanethiol (4-FBMT), and 4-chlorobenzenemethanethiol (4-CBMT) on Au(111) were examined using scanning tunneling microscopy (STM) and Kelvin probe (KP) to explore the structure and electronic interface properties of eight differently substituted aromatic thiol SAMs on Au(111). And these values are compared with gas phase dipole moments computed by quantum chemical calculations for individual thiol molecules. It was revealed that all eight thiol-molecules form uniform SAMs on Au(111) at $75^{\circ}C$ compared to lower solution temperature by STM observation. The work function change obtained in the KP measurements and calculated molecular dipole moments have the linear relationship while the 4-FBMT and 4-CBMT deviate from this tendency.

• The Journal of Natural Sciences
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• v.4
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• pp.1-10
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• 1991

The expression of the cloned Saccharomyces cerevisiae antioxidant protein gene in E. coil on plasmid was studied. Introduction of the DNA encoding yeast thiol-specific antioxidant protein into expression vector, PKK 223-3, having the tac promoter resulted in the production in E. coil of a Mr 27,000 polypeptide. This protein represented as much as about 1% of the bacterial soluble protein and showed the thiol-specific antioxidant properties. The bacterial protein showed physico-chemical properties indistringuishable from those of the yeast protein.

• Polymer(Korea)
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• v.24 no.5
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• pp.579-588
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• 2000

The effects of protective colloids on the colloid stability of poly(vinyl acetate) (PVAc) latex was investigated. The stability of PVAc latex in reactive poly(vinyl alcohol) mono thiol (PVALT) (DP=1080) having 78.4% saponification value was better than poly (vinyl alcohol)(PVA) (DP=1100) having 81.6% saponification value. The colloidal stability of PVAc latex particles improved drastically with increase of the reactive PVALT. The particle surface morphology of PVAc latex was examined by transmission electron microscopy (TEM). It was shown that particle size of 1ha latexes decreased with increasing reactive PVALT concentration. Therefore, the stabilities of latex for reactive PVALT protective colloid was superior to that of PVA ones. This result is due to the introduction of many thiol groups that induce chemical bonds at PVAc latexes surface, so that the formation of PVALT-b-PVAc block copolymer via the reaction of PVAc with reactive PVALT. In addition, zeta potential of the PVAc latexes decreased with increasing sodium carbonate concentration.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.76-82
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• 2014

1-Methylimidazole-2-thiol, as a kind of mercaptans, is a typical organic pollutant which has not been efficiently removed. In this study, titanium dioxide ($TiO_2$) photocatalyst based on magnetic multi-walled carbon nanotubes (MWCNTs) was synthesized via hydrothermal and sol-gel methods. The as-prepared photocatalyst was extensively characterized by X-ray diffraction (XRD), X-ray energy diffraction spectrum (EDS), transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectra, UV-Vis diffuse reflectance spectra (UV-vis DRS) and vibrating sample magnetometer (VSM). This photocatalyst of $TiO_2$/$Fe_3O_4$/MWCNTs was proved to exhibit high photocatalytic efficiency and the photodegradation rate could reach nearly 82.7% for the degradation of 1-methylimidazole-2-thiol under ultraviolet irradiation. In addition, the results demonstrated that inorganic ions had a negative impact on photodegradation of 1-methylimidazole-2-thiol to varying degrees. Moreover, pH had a great and complex effect on photocatalytic degradation of 1-methylimidazole-2-thiol under ultraviolet irradiation.

• KSBB Journal
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• v.19 no.6 s.89
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• pp.462-466
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• 2004

Mycothiol (MSH), a low molecular antioxidant thiol compound, was purified and analyzed from Streptomyns coelicolor A[3]2 by the monobromobimane fluorescence detection method modified by this lab. Through HPLC chromatpgram, MSH fraction was obtained following the elution time of standard MSH (donated by Dr. Robert C. Fahey). That MSH showed the highest concentration among the thiol compounds contained in the cell indicated that MSH was the key thiol compound having antioxidant activity. To understand the role of gene of inositol monophosphatase (I-1-Pase) involved in the MSH biosynthesis, it was isolated from S. coelicolor A(3)2 and cloned and overexpressed in the Escherichia coli. The expressed I-1-Pase was purified through Ni-NTA column. The soluble protein consisted of 281 amino acids, and the molecular weight was 32 kDa. I-1-Pase of S. coelicolor A(3)2 had the sequence homology with those of human and E. coli by 24 and $25\%$, respectively, and had two conserved domains (mofif A and motif B) which were typical of I-1-Pase.

• 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.

• 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

• 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)

• 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.

• Korean Journal of Chemical Engineering
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• v.35 no.12
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• pp.2421-2429
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• 2018

Thiol-based self-assembled anchor linked to glucose oxidase (GOx) and gold nanoparticle (GNP) cluster is suggested to enhance the performance of glucose biosensor. By the adoption of thiol-based anchors, the activity of biocatalyst consisting of GOx, GNP, polyethyleneimine (PEI) and carbon nanotube (CNT) is improved because they play a crucial role in preventing the leaching out of GOx. They also promote electron collection and transfer, and this is due to a strong hydrophobic interaction between the active site of GOx and the aromatic ring of anchor, while the effect is optimized with the use of thiophenol anchor due to its simple configuration. Based on that, it is quantified that by the adoption of thiophenol as anchor, the current density of flavin adenine dinucleotide (FAD) redox reaction increases about 42%, electron transfer rate constant ($k_s$) is $9.1{\pm}0.1s^{-1}$ and the value is 26% higher than that of catalyst that does not use the anchor structure.