• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.757-763
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• 1999

The metal specificity of D-xylose isomerase from Streptomyces rubiginosus was examined by site-directed mutagenesis. The activation constants for metal ion ($Mg^{2+},{\;}Mn^{2+},{\;}or{\;}Co^{2+}$) of wild-type and mutant enzymes were determined by titrating the metal ion-free enzyme with $Mg^{2+},{\;}Mn^{2+},{\;}and{\;}Co^{2+}$, respectively. Substitutions of amino acids either on coordinated or around the M2 site (His-22O, Asn-185, Glu-186, and Glu-221) dramatically affected the activation constants as well as activity. A decrease of metal binding affinity was most significant in the presence of $Mg^{2+}$. When compared with the wild-type enzymes, the binding affinity of H220S and Nl85K for Mg^{2+} was decreased by 10-15-fold, while the affinity for $Mn^{2+}{\;}or{\;}Co^{2+}$ only decreased by 3-5-fold. All the mutations close to the M2 site changed their metal preference from $Mg^{2+}{\;}to{\;}Mn^{2+}{\;}or{\;}Co^{2+}$. These altered metal preferences may be caused by a relatively weak binding affinity of $Mg^{2+}$ to the enzyme. Thermal inactivation studies of mutants at the M2 site also support the importance of the M2 site geometry for metal specificity as well as the thermostability of the enzyme. Mutations of other important groups hardly affected the metal preference, although pronounced effects on the kinetic parameters were sometimes observed. This study proposes that the metal specificity of D-xylose isomerase can be altered by the perturbation of the M2 site geometry, and that the different metal preference of Group I and GroupII D-xylose isomerases may be caused by nonconserved amino acid residues around the M2 site.

• Asia pacific journal of information systems
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• 제16권4호
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• pp.121-149
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• 2006

This study tries to explain how the relationship-specificity of invested assets affects E-collaboration and consequently on performance of Small and Medium Enterprises (SMEs). We classify the relationship-specificity of invested assets into four types such as business process specificity, physical asset specificity, domain knowledge specificity, and site specificity. We define E-collaboration as composed of Electronic Information Sharing (EIS) and Electronic Cooperation (E-Co). In addition, we articulate firm's performance as operational and strategic one, and investigate the impacts of EIS and E-Co on its performance. The data were collected from 187 SMEs and used for analysis. Based on the survey results, we find the following: (1) EIS is directly influenced by business process specificity and physical asset specificity, (2) E-Co is affected by site specificity and domain knowledge specificity, (3) EIS has a positive and significant impact on E-Co, (4) EIS affects firm's operational performance, (5) E-Co influences on firm's strategic performance. In conclusions, the higher the level of EIS, SMEs seem to get greater operational performance, Respectively, the higher the level of E-Co, they tend to get greater strategic performance.

• Bulletin of the Korean Chemical Society
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• 제27권1호
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• pp.59-64
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• 2006

Unlike other viral polymerases, HCV RNA-dependent RNA polymerase (RdRp) has not been successfully inhibited by nucleoside analogues presumably due to its strong substrate specificity for RNA. Thus, in order to understand the RNA-specificity of HCV RdRp, the structural characteristics of the active site was investigated. The hereto unknown 2-OH binding pocket at the active site of RdRp provides invaluable implication for the development of novel anti-HCV nucleoside analogues.

• Korean Journal of Radiology
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• 제23권1호
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• pp.52-59
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• 2022

Objective: To investigate whether the diagnostic performance of CT angiography (CTA) could be improved by modifying the conventional criterion (anastomosis site abnormality) to diagnose hepatic artery occlusion (HAO) after liver transplantation (LT) in suspected patients with Doppler ultrasound (US) abnormalities. Materials and Methods: One hundred thirty-four adult LT recipients (88 males and 46 females; mean age, 52.7 years) with suspected HAO on Doppler US (40 HAO and 94 non-HAO according to the reference standards) were included. We evaluated 1) abnormalities in the HA anastomosis, categorized as a cutoff, ≥ 50% stenosis at the anastomotic site, or diffuse stenosis at both graft and recipient sides around the anastomosis, and 2) abnormalities in the distal run-off, including invisibility or irregular, faint, and discontinuous enhancement. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of the conventional (considering anastomosis site abnormalities alone) and modified CTA criteria (abnormalities in both the anastomosis site and distal run-off) for the diagnosis of HAO were calculated and compared using the McNemar test. Results: By using the conventional criterion to diagnose HAO, the sensitivity, specificity, PPV, NPV, and accuracy were 100% (40/40), 74.5% (70/94), 62.5% (40/64), 100% (70/70), and 82.1% (110/134), respectively. The modified criterion for diagnosing HAO showed significantly increased specificity (93.6%, 88/94) and accuracy (93.3%, 125/134) compared to that with the conventional criterion (p = 0.001 and 0.002, respectively), although the sensitivity (92.5%, 37/40) decreased slightly without statistical significance (p = 0.250). Conclusion: The modified criterion considering abnormalities in both the anastomosis site and distal run-off improved the diagnostic performance of CTA for HAO in suspected patients with Doppler US abnormalities, particularly by increasing the specificity.

• BMB Reports
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• 제31권4호
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• pp.399-404
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• 1998

In order to gain further insight on the relationship between structure and function of glutathione S-transferase (GST), the six active-site mutants, R13T, K44T, Q51A, Q64A, S65A, and D98A, of human GST P1-1 were expressed in Escherichia coli and purified to electrophoretic homogeneity by affinity chromatography on immobilized GSH. The active-site mutants showed marked differences in substrate specificity. The substitution of Gln51 with threonine resulted in a drastic decrease in the specific activities to <10% of the wild-type value. The substitution of Arg13 with threonine resulted in more decreased specific activity toward cumene hydroperoxide and in the $I_{50}$ values of S-(2,4-dinitrophenyl) glutathione and benanstatin A. These results suggest that the substitution of Arg13 with threonine changes the conformation of the active site to increase the affinity for the product or electrophilic substrate. Lys44 seems to be in the vicinity of the H-site of hGST P1-1 or may contribute to some extents to the electrophile binding.

• KSBB Journal
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• 제9권1호
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• pp.63-71
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• 1994

During the last decade enzyme reaction in organic solvent has been studied to show that specificity in buffer is different from that in organic solvent. The specificity of restriction enzyme was effected by various factors such as ionic strength, salt organic solvent and temperature. In this study, restriction enzyme PvuII which is used most frequently in genetic engineering and the substrate was vector pGEM3 whose sequence was already known were used. As a result the recognition sequence site was changed in the presence of organic solvents whose Log P are -1.5∼0. Their specificities were contrast with activities were contrasted. Specificities were not changed in organic solvent easily in inactivating enzyme. We think that the enzyme recognition site was not changed randomly but by preferential order. A recombinant vector which does not contain typical cleavage site CAG↓CTG was cleaved in 20% ethanol solution. This result might show that restriction enzyme could be used to cleave at unusual sites by changing the reaction conditions.

• 만화애니메이션 연구
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• 통권47호
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• pp.335-356
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• 2017

국내 캐릭터산업의 발전과 함께 산업적 콘텐츠로써의 캐릭터와 함께 공공캐릭터에 대한 관심도가 높아지고 있다. 공공캐릭터란 특정 지역, 기관, 단체, 조직, 행사 등의 구성원이 공유하거나 지향하는 상징성을 함축적으로 표현하고 있는 비영리적 캐릭터이다. 특정의 개인이나 단체의 이윤을 목적으로 하는 상업디자인과 구별되며, 디자인의 주체와 객체, 지향하는 가치, 역할 등에 있어 시민의 안녕과 행복과 같은 사회적인 가치를 추구하는 공공디자인의 목적과 부합하는 역할을 부여받았다. 공공캐릭터는 지자체 캐릭터 개발을 중심으로 발전하기 시작했으나, 대부분의 캐릭터가 활용되지 못했다. 그러나 공공캐릭터에 대한 관심이 높아지면서 캐릭터를 활용하여 지역에 대한 고유성과 정체성을 표현하기 위한 수단으로 다시금 환영받고 있다. 본 논문은 공공캐릭터가 가지는 지역에 대한 정체성 표현을 장소특정성(Site-Specificity)에 대입하여 연구해보고자 한다. 장소특정성은 동시대미술에서 장소에 초점을 맞춘 미술, 특정 장소 및 상황에 의해 의미가 생성되는 작품을 의미한다. 현재 공공캐릭터는 주로 한 지역 또는 기관을 대표하는 역할을 맡은 바, 어느 공동체 속에 속해있느냐에 따라 정체성과 그에 따른 가치를 판단할 수 있다. 이를 통해 지역 속 캐릭터가 공공디자인으로써 어떠한 사회적 의미를 가지는지에 대해 연구하고자 한다.

• BMB Reports
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• 제46권1호
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• pp.37-40
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• 2013

CY-007 and CY-049 pteridine glycosyltransferases (PGTs) that differ in sugar donor specificity to catalyze either glucose or xylose transfer to tetrahydrobiopterin were studied here to uncover the structural determinants necessary for the specificity. The importance of the C-terminal domain and its residues 218 and 258 that are different between the two PGTs was assessed via structure-guided domain swapping or single and dual amino acid substitutions. Catalytic activity and selectivity were altered in all the mutants (2 chimeric and 6 substitution) to accept both UDP-glucose and UDP-xylose. In addition, the wild type activities were improved 1.6-4.2 fold in 4 substitution mutants and activity was observed towards another substrate UDP-N-acetylglucosamine in all the substitution mutants from CY-007 PGT. The results strongly support essential role of the C-terminal domain and the two residues for catalysis as well as sugar donor specificity, bringing insight into the structural features of the PGTs.

• 대한건축학회논문집:계획계
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• 제35권2호
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• pp.93-104
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• 2019

Minimal art, which began to flourish in the mid-1960s, explores perceptual situations caused by the involvement of objects in given site contexts. This has led to the mentions of minimal art as a site-specific art, but its limitations have also been pointed out. This study specifically addresses the limitations of minimal art as a site-specific art with two perceptual points of view. First, according to Michael Fried, situations described as 'now here' focus largely on the bodily experiences of a place. However, they do not rooted in specific time and space of a certain place. Second, the unique characteristics of a certain place are excluded from the perception of the body which occupies the passage of time. Self-sufficient algorithm, which is far from site-specific conditions, is the autonomous system creating the period in the way of arrangement of objects. In addition, Minimal art regards a body only as the objectivity excluding the subjectivity which is essential creating meaning in a place. In the latter part of the article, these features are dealt with through Donald Judd's works. This study on site-specificity also provides a new perspective on the discussion of Minimal architecture and Minimal landscape.

• 한국의상디자인학회지
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• 제13권4호
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• pp.189-198
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• 2011

The existing approaches to the body painting have been dominated by the angles focused on the 'performance' and the 'body art'. The performance-focused approach, in which body painting serves simply as a make-up for the performer, one of the elements of performance to help it communicate effectively its meaning and come to perfection, might be in itself lacking in the attention to the placement of the body painting as a new genre of art. This thesis has two aims to explain the concept of Allegory as the contemporary meaning and to examined the formative characteristics and other characteristics of Allegory through theoretical research. For this purpose, this study is based upon allegorical cognition of Walter Benjamin and the allegorical method of Craig Owens. The formative characteristics of allegory are summarized as appropriation, deconstruction and site-specificity as follows. First, the constructed result has contrived characters because its image which derived from body painting based on the past shown image. Second, Allegoric body painting refuses an aesthetically valuable piece which can be interpreted formal completion, it shows intactly deconstruction of its configuration, substance and style. Third, Allegoric body painting has site-specificity facts which can be expressed for diverse meanings. Through these facts, the final goal of this thesis will find specific character for Allegory and apply to body painting.