• Korean Journal of Microbiology
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• v.40 no.2
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• pp.87-93
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• 2004

Dynamic modification of cytoplasmic and nuclear proteins by O-linked N-acetylglucosamine (O-GlcNAc) on Ser and Thr residues is ubiquitous in higher eukaryotes. And this modification may serve as a signaling mod-ification analogous to protein phosphorylation. Addition and cleavage of O-GlcNAc are catalyzed by O-linked GlcNAc transferase (OGT) and O-linked N-acety1glucosaminidase (O-GlcNAcase), respectively. Two types of human O-GlcNAcase gene were cloned and expressed as three fusion proteins in Escherichia coli. O-GlcNA-case activity showed in the order of thioredoxin fusion> $6{\times}His$ tag> GST fusion. O-GlcNAcase had enzy-matic activity against only ${\rho}$NP-GlcNAc of seven tested substrate analogs. Blast search revealed that O-GlcNAcase has two conserved domains, amino terminal hyaluronidase-like domain and carboxy terminal N-acetyltransferase domain. Extensive deletion studies were done to define catalytically important domains. The deletions of hyaluronidase-like domain and N-acetyltransferase domain abolished enzyme activity. But, N-ter-minal 55 amino acid deletion and C-terminal truncation showed lower activity. Based on deletion analysis, we suggest that hyaluronidase-like domain is essential for enzyme activity and carboxy terminal N-acetyltrans-ferase domain may be modulatory function.

• Applied Biological Chemistry
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• v.12
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• pp.43-51
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• 1969

The purpose of this study was to determine protein amino acid contents of some Korean foods by gas-liquid chromatography, and to evaluate this technique as a procedure for the quantitative determination of amino acids in foods. The crude protein content of foods was also estimated from the nitrogen content. 1. Nitrogen content of each food sample was determined previously to adjust the amount of sample for GLC analysis 2. In the analysis of 17 known amino acids, a linear relationship was found between the weight of 13 amino acids of 17 amino acids, the internal standard as well as the injection volume of a mixture and the detector responses for the derivatives of the amino acids. No response for arginine, cystein, histidine, and tyrosine was observed. 3. The relative molar response (RMR) values for the 13 amino acids of standard solution relative to glutamic acid as '1.00' were obtained under normal operating conditions with a hydrogen flame ionization detector. 4. The recovery of amino acids from their mixtures with natural food materials was carried out. The recoveries were essentially quantitative except threonine and serine. An overall mean recovery of 11 amino acids was $101.4{\pm}8.4$ per cent before hydrolysis and $98.1{\pm}8.7$ per cent after hydrolysis of samples. 5. The comparative analysis of the acid hydrolysates of two food samples by gas-liquid and ion-exchange chromatographic analysis were carried out. In white-bait pemmican, only threonine and asparagine amounts by GLC analysis had similar values to those obtained by ion-exchange chromatography. The other seven amino acids gave higher values as measured by GLC than by ion-exchange. With the food sample, soybean, alanine, valine, asparagine, and glutamic acid were in good agreement in two analysis, while leucine, proline, threonine, phenylalanine, and lysine were found in slightly higher concentrations in the GLC analysis. 6. Grant variations of amino acid content were found among samples analyzed. The amino acid contents of each sample were compared with the values found in the literature.

• Journal of Digital Convergence
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• v.10 no.1
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• pp.215-228
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• 2012

This study aims to answer the research question of what are the global leadership competencies(GLC) and what is the integrating framework of GLC? To attain the goal of reframing the GLC models with systematic research on GLC, the specific objectives are delineated as follows; the first objective is to identify the area of GLC. The second one is to extract the dimensions agreed with consensus. The third one is to suggest the reframed GLC model. Through the literature review and content analysis about GLC and global mindset, the two dimensions-subject and objects-of GLC model are emerged to classify the existing clusters of GLC. The extracted objects are self, others, culture, business, and global world. The dimension of subject who is global leader is more specifically divided into the knowing/doing process and three aspects of human activity like cognitive, emotional, and behavioral one. GLC are reframed and rearranged based on the two dimensions. As a results new framework for GLC with 11 clusters are presented. Knowing group of GLC contains personal, social, cultural, business literacy, and global mindset. Doing group of GLC contains personal, social, cultural, business savvy, and global change. Personal traits as a core character are at the core of the knowing and doing process of the self. Lastly, the implications and limitations of this research are suggested, and suggestion for further research is followed.

• Korean Journal of Microbiology
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• v.40 no.2
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• pp.147-153
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• 2004

Protein modification by N-acetyl-${\beta}$-D-glucosamine (O-G1cNAc) on the hydroxyl groups of Ser or Thr ubiq-uitously occurs in eukaryotic cells and is involved in many cellular phenomena. The level of O-G1cNAc-mod-ified protein is regulated by OGT and O-GlcNAcase enzymes. We have tried to produce recombinant O-GlcNAcase in E. coli as an effort to establish in vitro screening system for modulators of O-GlcNAcase. The culture conditions for improvement of O-GlcNAcase productivity, were as follows: induction temperature, $30^{\circ}C$; the concentration of L-arabinose, 0.02% and induction time, 5 hr. Under these culture conditions, E. coli cells containing O-GlcNAcase gene had no enzyme activity until up to 3 hr culture. However, O-GlcNAcase activity dramatically increased from 3 to 5 hr culture. It almost maintained the same level after 5 hr culture. Western blot analysis verified the amount of expressed O-GlcNAcase increased with culture time, being con-sistent with activity data. The optimal reaction condition determined in this study was as follows: protein quan-tity, $5{\mu}g$; reaction time, 30 min; reaction temperature, $45^{\circ}C$; substrate concentration, 2 mM; reaction pH, 6.5. Methanol had little effect on O-GlcNAcase activity and 90% of activity were retained at 10%. Only 15% resid-ual activity were detected at 5% of chloroform.

• BMB Reports
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• v.40 no.6
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• pp.1058-1068
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• 2007

The post-translational modifications of Ser and Thr residues by O-linked $\beta$-N-acetylglucosamine (O-GlcNAc), i.e., O-GlcNAcylation, is considered a key means of regulating signaling, in a manner analogous to protein phosphorylation. Furthermore, it has been suggested that the increased flux of glucose through the hexosamine biosynthetic pathway (HBP) stimulates O-GlcNAcylation, and that this may be responsible for many of the manifestations of type 2 diabetes mellitus. To determine whether excessive O-GlcNAcylation of target proteins results in pancreatic $\beta$ cell dysfunction, we increased nucleocytoplasmic protein O-GlcNAcylation levels in $\beta$ cells by exposing them to streptozotocin and/or glucosamine. Streptozotocin and glucosamine co-treatment increased O-GlcNAcylated proteomic patterns as assessed by immunoblotting, and these increases in nuclear and cytoplasmic protein O-GlcNAcylations were accompanied by impaired insulin secretion and enhanced apoptosis in pancreatic $\beta$ cells. This observed $\beta$cell dysfunction prompted us to examine Akt and Bcl-2 family member proteins to determine which proteins are O-GlcNAcylated under conditions of high HBP throughput, and how these proteins are associated with $\beta$ cell apoptosis. Eventually, we identified ten new O-GlcNAcylated proteins that were expressed during $\beta$ cell apoptosis, and analyzed the functional implications of these proteins in relation to pancreatic $\beta$ cell dysfunction.

• Journal of Ginseng Research
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• v.9 no.1
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• pp.54-63
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• 1985

The free phenolic fraction from Korean white ginseng (Panax ginseng C.A. Meyer) was studied by GLC/MS as trimethylsilyl and methyl derivative. Five phenolic compounds such as 2,6-ditert butyl p-crestal, phloroglucinol, protocatechuic acid, isoferulic acid, quinic acid were identified newly. And additionally 13 organic acids and hydrocarbons were also identified in the fraction.

• Korean Journal of Remote Sensing
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• v.35 no.1
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• pp.83-92
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• 2019

Land cover (LC) is an important factor in socioeconomic and environmental studies. According to various studies, a number of LC maps, including global land cover (GLC) datasets, are made using polar orbit satellite data. Due to the insufficiencies of reference datasets in Northeast Asia, several LC maps display discrepancies in that region. In this paper, we performed a feasibility assessment of LC mapping using Geostationary Ocean Color Imager (GOCI) data over Northeast Asia. To produce the LC map, the GOCI normalized difference vegetation index (NDVI) was used as an input dataset and a level-2 LC map of South Korea was used as a reference dataset to evaluate the LC map. In this paper, 7 LC types(urban, croplands, forest, grasslands, wetlands, barren, and water) were defined to reflect Northeast Asian LC. The LC map was produced via principal component analysis (PCA) with K-means clustering, and a sensitivity analysis was performed. The overall accuracy was calculated to be 77.94%. Furthermore, to assess the accuracy of the LC map not only in South Korea but also in Northeast Asia, 6 GLC datasets (IGBP, UMD, GLC2000, GlobCover2009, MCD12Q1, GlobeLand30) were used as comparison datasets. The accuracy scores for the 6 GLC datasets were calculated to be 59.41%, 56.82%, 60.97%, 51.71%, 70.24%, and 72.80%, respectively. Therefore, the first attempt to produce the LC map using geostationary satellite data is considered to be acceptable.

• Korean Journal of Environmental Agriculture
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• v.17 no.1
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• pp.22-25
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• 1998

These studies were conducted to develope analysis method of herbicide quizalofop-ethyl by Gas Liquid Chromatography(GLC) and Enzyme-Linked Immunosoment Assay(ELISA) in soil and plant. Quizalofop produced by hydrolysis of quizalofop-ethyl was conjugated with bovine serum albumin(BSA). Quizalofop antibody was developed in rabbits by using BSA conjugation. Antibody titer, incubation temperature, and incubation time was 32,000, $37^{\circ}C$ and 4hours respectively. Minimum detection limit of quizalofop-ethyl by ELISA was 5ppb. Quizalofop-ethyl recovery from soil by ELISA was more than 95percent. Minimum detection limit of quizalofop-ethyl by GLC was 5ppb. Quizalofop-ethyl recovery from soil by GLC was from 89 percent to 100 percent. Minimun detection limit of quizalofop-ethyl by HPLC was 100ppb. Quizalofop-ethyl recovery from soil by HPLC was 89.6 percent.

• Food Science and Biotechnology
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• v.15 no.6
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• pp.851-855
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• 2006

Acarviosine-glucose (AcvGlc) is an ${\alpha}$-glucosidase inhibitor and has similar inhibitory activity to acarbose in vitro. We synthesized AcvGlc by treating acarbose with Bacillus stearothermophilus maltogenic amylase and fed C57BL/6J and db/db mice with diets containing purified AcvGlc and acarbose for 1 week. AcvGlc (50 and 100 mg/100 g diet) significantly reduced plasma glucose and triglyceride levels in db/db mice by 42 and 51 %, respectively (p<0.0001). The hypoglycemic and hypotriglyceridemic effects of AcvGlc were slightly, but significantly, greater than those seen with acarbose treatment (p<0.0001) in C57BL/6J mice. In an oral glucose tolerance test, glucose tolerance was significantly improved at all time points (p<0.01). The expression of two novel glucose transporters (GLUTs), GLUT10 and GLUT12, were examined by Western blot analysis. GLUT10 was markedly increased in the db/db livers. After AcvGlc treatment, the expression of hepatic GLUT10 was decreased whereas intestinal GLUT12 was significantly increased in both strains of mice. Our results show that AcvGlc improves plasma lipid and glucose metabolism slightly more than acarbose. Regulation of hepatic GLUT10 and intestinal GLUT12 may be important in controlling blood glucose levels.

• Journal of Life Science
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• v.19 no.8
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• pp.1062-1066
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• 2009

N-Acetylglucosamine kinase (GlcNAc kinase or NAGK; EC 2.7.1.59) catalyzes the phosphorylation of GlcNAc to GlcNAc-6-phosphate (GlcNAc-6-P). Despite detailed characterization of the enzyme itself, there have been few studies on the expression of NAGK in mammalian tissues. In the rat hippocampal neuron in culture, NAGK-immunoreactivity (IR) formed clusters in somatodendritic domains. In this study we characterized the NAGK clusters that protrude out the long axis of dendritic shafts. By double-labeling of the neurons with antibodies against NAGK and various synaptic proteins, we show that NAGK is positioned at the base of spines, while there were no NAGK protrusions into inhibitory postsynaptic sites. Immunoblot analysis showed that NAGK was included in synaptosomes but not in PSD fractions. Our results indicate that the NAGK clusters at the dendritic periphery protrude into spines.