• Microbiology and Biotechnology Letters
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• v.35 no.3
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• pp.196-202
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• 2007

Mutations in the cystathionine ${\beta}$-synthase (CBS) gene cause homocystinuria, the most frequent inherited disorder in sulfur metabolism. CBS is the unique enzyme using both heme and pyridoxal 5-phosphate (PLP) for activity. Among the reported 140 mutations, one of the most common disease-causing alterations in human CBS is G307S mutation. To investigate the pathogenic mechanism of G307S by spectroscopic methods, we engineered the full length and the truncated G247S mutation of yeast CBS that is corresponding mutation to human G307S. Yeast CBS does not contain heme and thus gives a merit to study the spectroscopic properties. The UV-visible spectra of the purified full length and the truncated G247S yeast CBSs showed the total absence of PLP in the protein. The absence of PLP in G247S mutation was also confirmed by the PLP-cyanide adduct formation experiment, which was conducted by the incubation of the purified enzyme with KCN. The adducts were detected using a circular dichroism (CD) and a spectrofluorimeter. Radio isotope activity assay of full length and truncated G247S proteins also gave no activity. Our yeast G247S mutation data suggested that G307S might make the distortion of the active site so that cofactor PLP and substrate can not fit inside the active site. Our yeast CBS study addressed the reason why the G307S mutation in human CBS makes the enzyme inactive that consequently leads to severe clinical phenotype.

• BMB Reports
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• v.28 no.5
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• pp.375-381
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• 1995

Two forms of glucoamylase (GI and GII) from starch-grown Lipomyces kononenkoae CBS 5608 mutant were purified to apparent homogeneity by means of ultrafiltration, Sephacryl S-200 gel filtration and DEAE Sephadex A-50 chromatography. The apparent molecular weight was calculated as ca. 150 kDa for GI and ca. 128 kDa for GII, respectively. Both enzymes were glycoproteins with isoelectric points of 5.6 (GI) and 5.4 (GII). They had a pH optimun of 4.5 and were stable from pH 5 to 8. The temperature optimum for both enzymes was $60^{\circ}C$, but they were rapidly inactivated above $70^{\circ}C$. The $K_m$ values toward starch were estimated to be 6.57 mg per ml for GI and 4.52 mg per ml for GII, and the $V_{max}$ values were 16.28 ${\mu}M$ per mg for GI and 32.25 ${\mu}M$ per mg for GII, respectively. The $K_m$ and $V_{max}$ values of GII for ${\alpha}-$ or ${\beta}-cyclodextrin$ were estimated to be 0.15 mg per ml and 2.0 mg per ml, respectively ($K_m$) and 1.02 ${\mu}M$ per mg or 1.02 ${\mu}M$ per mg, respectively ($V_{max}$). Neither enzyme exhibited pullulanase activity but they released only glucose from starch or cyclodextrin. Amino acid analysis indicated that both glucoamylases were enriched in proline and acid amino acids. Glucoamylase GII strongly cross-reacted with a monoclonal antibody raised against GI enzymes, and the two enzymes shared very similar amino acid composition. Western blot analysis indicated that L. kononenkoae CBS 5608 mutant produced two forms of glucoamylase on starch, and that synthesis of them was subject to glucose repression.

• Bulletin of the Korean Chemical Society
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• v.23 no.1
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• pp.103-106
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• 2002

A new reaction mechanism is proposed for the reaction of thianthrene cation radical perchlorate $(Th^{+{\cdot}}CIO_4^-}$ and tert-butyl peroxide in acetonitrile at room temperature on the basis of experimental and theoretical results. Rapid C-O bond rupture instead of O-O bond cleavage was observed by a good peroxy radical trapping agent, thianthrene cation radical. Products were N-tert-butyl acetamide, thianthrene 5-oxide (ThO), thianthrene 5,5-dioxide $(SSO_2)$, and thianthrene (Th). Thianthrene 5,10-dioxide (SOSO) was not obtained. A comparative computational study of the cation radical of tert-butyl peroxide is made by using B3LYP and CBS-4. The computational results are helpful to explain the reaction mechanism.

• Carbon letters
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• v.26
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• pp.25-30
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• 2018

The dielectric medium used in electrophoretic displays (EPDs) is required to be an environmentally friendly solvent with high density, low viscosity, and a large electric constant. Hydrofluoroether, a highly fluorinated solvent with eco-friendly characteristics, is regarded as a viable alternative medium for EPDs, owing to the similarity of its physical properties to those of the conventional EPD medium. Surface modification of particles is required, however, in order for it to disperse in the charged solvent. Also, positive/negative charges should be present on the particle surface to enable electrophoretic behavior. In this study, carbon black particles wrapped with positively charged nitrogen (N-CBs) were fabricated by a simple hydrothermal process using a poly(diallyldimethylammonium chloride) solution as a black coloring agent for the EPD. The dispersion behavior of N-CBs was investigated in various solvents.

• Carbon letters
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• v.12 no.4
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• pp.252-255
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• 2011

Carbon-based electric double-layer capacitors are being evaluated as potential energy-storage devices in an expanding number of applications. In this study, samples of carbon black (CB) treated at different temperatures ranging from $650^{\circ}C$ to $1100^{\circ}C$ were used as electrodes to improve the efficiency of a capacitor. The surface properties of the heat-treated CB samples were characterized by X-ray photoelectron spectroscopy and X-ray diffraction. The effect of the heat-treatment temperature on the electrochemical behaviors was investigated by cyclic voltammetry and in galvanostatic charge-discharge experiments. The experimental results showed that the crystallinity of the CBs increased as the heat-treatment temperature increased. In addition, the specific capacitance of the CBs was found to increase with the increase in the heat-treatment temperature. The maximum specific capacitance was 165 $F{\cdot}g-1$ for the CB sample treated at $1000^{\circ}C$.

• Korean Journal of Microbiology
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• v.22 no.1
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• pp.49-56
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• 1984

Formation and regeneration of protoplasts by Novozym 234 from Kluyveromyces fragilis N100 and Candida pseudotropicalis CBS607 were studied. This enzyme was more effective on cells grown at exponential phase than those at stationary one to convert intact cells into protoplasts. As osmotic stabilizer, ammonium sulphate was suitable for not only protoplast formation but also regeneration in K. fragilis as well as in C. pseudotropicalis. Optimal enzyme concentration was 3mg per ml in K. fragilis and 1~3mg per ml in C. pseudotropicalis, respectively. After the exposure of K. fragilis cells to 3mg per ml of enzyme for 3hr at 30$^{\circ}C$ , approximately 95% of protoplast formation of all observed cells was obgained, while about 100% from C. pseudotropicalis under the same condition was produced. The regeneration frequency of protoplasts by this enzyme was much lower than that by snail enzyme(Glusulase) although Novozym 234 converted cells from above two species into protoplasts free of cell debris effectively, compared with Glusulase. Novozym 234 appears to be suitable for subcellular fractionation to obtain nuclei or other organelles rather than protoplast regeneration.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.952-957
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• 2008

A Gram-negative bacterium, named LY402, was isolated from contaminated soil. 16S rDNA sequencing and measurement of the physiological and biochemical characteristics identified it as belonging to the genus Enterohacter. Degradation experiments showed that LY402 had the ability to aerobically transform 79 of the 91 major congeners of Aroclor 1242, 1254, and 1260. However, more interestingly, the strain readily degraded certain highly chlorinated and recalcitrant polychlorinated biphenyls (PCBs). Almost all the tri- and tetra-chlorobiphenyls (CBs), except for 3,4,3',4'-CB, were degraded in 3 days, whereas 73% of 3,4,3',4'-, 92% of the penta-, 76% of the hexa-, and 37% of the hepta-CBs were transformed after 6 days. In addition, among 12 octa-CBs, 2,2',3,3',5,5',6,6-CB was obviously degraded, and 2,2',3,3',4,5,6,6'- and 2,2',3,3',4,5,5',6'-CB were slightly transformed. In a metabolite analysis, mono- and dichlorobenzoic acids (CBAs) were identified, and parts of them were also transformed by strain LY402. Analysis of PCB degradation indicated that strain LY402 could effectively degrade PCB congeners with chlorine substitutions in both ortho- and para-positions. Consequently, this is the first report of an Enterobacteria that can efficiently degrade both low and highly chlorinated PCBs under aerobic conditions.

• Journal of Korean Society of Forest Science
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• v.104 no.1
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• pp.76-83
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• 2015

Old growth and protected-trees are worth history and culturally in Korea. This research carried out to investigate habitat characterization and the vegetative propagation methods of Salix chaenomeloides(100-600 years old trees) in Gyeongsangnamdo Province. It has been preserved in good and grow naturally in area surrounding village(4 trees), riverside(1 tree) and field(1 tree). Cutting from old growth and protected trees was conducted using 10 kinds of bedsoils. It was survived above 93% in all bedsoils. Growth of cuttings is a distinct difference according to bedsoils and tree ages. Growth of cutting was high on CBS, followed mixed bedsoils(VPMP) including vermiculite, peatmoss and perlite. Root collar diameter was difference depend on tree ages and bedsoils. All trees are produced 1 to 4 branch. Root growth of cutting was 20 cm on CBS and VPMP, which is the best shoot growing on cutting. Bedsoil with physico-chemical characteristics of high moisturizing ability, high air permeability, high EC value and slightly acid may be suitable for efficiently cutting propagation of old growth and protected S. chaenomeloides. CBS and VPMP bedsoil are favorable for propagating this species by cuttings.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.E1
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• pp.13-21
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• 2005

Atmospheric concentrations of PCBs were monitored in Ansung-city, Kyonggi province during the 2001/2002 to characterize the concentration distribution and seasonal variation of particle polychlorinated biphenyls (PCBs). Average concentration of particle bound PCB showed maximum value for penta-CBs and minimum value for octa-CBs. Seasonal contributions $(%\)$ of total particle PCBs showed the highest value in winter months and lowest value in summer month, This result indicated that concentration of total particle PCBs increased with decreasing temperature in the atmosphere. Therefore, particle PCBs were easily formed by the condensation of gas phase PCBs in winter months. The total particle PCBs exhibited an inverse correlation with temperature (p<0.01) which suggested that particle PCBs were easily formed by condensation of gaseous PCBs in winter months.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.160-161
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• 2011

최근 IT 기술의 발전으로 TV, DMB, 이동통신망 등을 이용한 효율적인 재난문자방송 서비스가 국내외에서 관심을 받고 있다. 특히. 이동통신망은 지역단위 전송이 가능하기 때문에 지진, 해일 등의 심각한 재난이 예상되는 지역에 신속한 경보 서비스를 가능하게 해준다. 국내에서는 이미 2G 이동통신망을 이용하여 대국민 재난문자방송 서비스를 실시하였다. 그러나 국내외적으로 3G/4G 이동통신망 서비스가 본격화 되었으며, 이에 맞는 재난문자방송 서비스가 필요한 실정이다. 이에 본 논문에서는 이동통신망을 이용한 재난문자방송 서비스인 CBS의 국내외 동향과 표준안 등을 소개하며, 국내 CBS의 향후 나아갈 방향을 제시하고자 한다.