• Journal of Life Science
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• v.24 no.1
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• pp.98-103
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• 2014

NAD(P)H quinone oxidoreductase 1 (NQO1) is a flavoprotein that catalyzes the two electron reduction of diverse substrates, including quinones. It uses NADH or NADPH as a cofactor for enzymatic machinery. In the metabolism of quinones, NQO1 has two conflicting functions because of the different stability of converted hydroquinones. The stable form of hydroquinone is excreted from cells by conjugation with glutathione or glucuronic acid. The unstable form of hydroquinone induces cell death by induction of oxidative stress and DNA damage. Certain quinones known as bio-reductive agents have a cytotoxic function following reduction by NQO1. Bio-reductive agents, such as ${\beta}$-lapachone or mitomycin C, induce the depletion of NAD(P)H and the generation of oxidative stress in an NQO1-dependent manner. NQO1 is highly expressed in several cancer tissues. Therefore, NQO1 is a good therapeutic target for cancer treatment with bio-reductive agents.

• Korean Journal of Microbiology
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• v.26 no.3
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• pp.197-206
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• 1988

An outer membrane-associated 2-furaldehyde dehydrogenase, catalyzing the oxidation of 2-furaldehyde to 2-furoic acid from Klebsiella pneumoniae was purified to homogeneity and characterized. The enzyme showed its highly specific dependency on $\beta$-$NAD^{+}$. Enzyme activity was monitored during purification by using substrate 2-furaldehyde and coenzyme $\beta$-$NAD^{+}$ by means of high performance liquid chromatography. The outer membrane was successfully collected by the methods of Percoll density gradient ultracentrifugation and ultracentrifugation after preferential solubilization of the membrane with $Mg^{2+}$ and Triton X-100. The enzyme was purified by the series of procedures including extraction of outer membrane protein with EDTA and lysozume, and fractionation by column chromatography on QAE-Sephades Q-50, and subsequently Sephadex G-100. The enzume showed its optimal activity at $85^{\circ}C$, pH 9.5, and in the presence of 1.5% (vol/vol) Triton X-100. The enzyme exhibited a native molecular size of 88,000 by nondenaturing polyacrylamide gel electrophoresis and had an apparent Km of 4.72mM for 2-furaldehyde.

• Animal cells and systems
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• v.9 no.4
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• pp.191-198
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• 2005

The effects of 6-aminonicotinamide (6-AN) on viability of IMR32 neuroblastoma cells in the presence of ATP or $NAD^+$ have been investigated. 6-AN caused marked reduction in cell viability and similar observations were also made with cells treated with 6-AN+ATP. However, cells treated with $6-AN+NAD^+$ showed cell viability similar to untreated cells. Morphologically, 6-AN and 6-AN+ATP treated cells showed loss of neurites, polyhedric shapes, shrinkage of cell bodies and formation of lysed cells, while $6-AN+NAD^+$ cells did not show any such changes. The flow cytometry analysis demonstrated that 6-AN increased cell population in $G_0/G_1$ phase and decreased cell population in Sand $G_2/M$ phase following a 72 h exposure. Western blot analysis showed that 6-AN stimulated a substantial increase in the level of the cdk inhibitor $p27^{kip1}$, but lowered the levels of cdk2, cyclin E and p-Rb. However, cdc25A and p53R2 were not significantly affected. Immunofluorscence staining of $p27^{kip1}$, cdk2, cyclin E and p-Rb revealed close correlation between the signal observed in the Western blot analysis. 6AN+ATP treated cells showed similar results obtained with 6-AN treated cells in expression of cdk2, cyclin E, p-Rb proteins and $p27^{kip1}$, $6-AN+NAD^+$ cells showed greater expression of cdk2, cyclin E and p-Rb than those in 6-AN and 6-AN+ATP treated cells. The results suggest that 6-AN induced the $G_0/G_1$ phase arrest in IMR32 neuroblastoma cell lines through the increase of $p27^{kip1}$ and the decrease of cdk2, cyclin E and p-Rb.

• Korean Journal of Microbiology
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• v.41 no.1
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• pp.67-73
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• 2005

Photoautotrophic bacteria are promising candidates for the production of poly(3-hydroxybutyrate) (PHB) since they can address the critical problem of substrate costs. In this study, we isolated 25 Tn5-inserted mutants of the Synechocystis sp. PCC 6803 which showed enhanced PHB accumulation compared to the wild-type strain. After 5-days cultivation under nitrogen-limited mixotrophic conditions, the intracellular levels of PHB content in these mutants reached up to $10-30\%$ of dry cell weight (DCW) comparable to $4\%$ of DCW in the wild-type strain. Using the method of inverse PCR, the affected genes of the mutants were mapped on the completely known genome sequence of Synechocystis sp. PCC 6803. As a result, the increased PHB accumulation in 5 mutants were found to be resulted from defects of genes coding for NADH-ubiquinone oxidoreductase, O-succinylbenzoic-CoA ligase, photosystem II PsbT protein or histidine kinase, which are involved in photosystem in thylakoid inner membrane of the cell. The values of $NAD(P)H/NAD(P)^+$ ratio in the cells of these mutants were much higher than that of the wild-type strain as measured by using pulse-amplitude modulated fluorometer, suggesting that PHB synthesis could be enhanced by increasing the level of cellular NAD(P)H which is a limiting substrate for NADPH-dependent acetoacetyl-CoA reductase. From these results, it is likely that NAD(P)H would be a limiting factor for PHB synthesis in Synechocystis sp. PCC 6803.

• Microbiology and Biotechnology Letters
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• v.19 no.6
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• pp.610-613
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• 1991

Some of the Kinetic properties of crystallic xanthine dehydrogenase form Pseudomonas synxantha A3 were studied. The enzyme activity was strongly inhibited by adenine, 8-azaadenine, 2-methyladenine, guanine, and 8-azaguanine, but not by caffeine, and the inhibitions by adenine and guanine were observed to be of noncompetitive type. The $K_i$ values for adenine and guanine were 0.037 and 0.098 mM, respectively. Michaelis constants were found to be 0.33 and 0.06 rnM for hypoxanthine and xanthine with $NAD^+$ as the second substrate, respectively, and 0.1 rnM for $NAD^+$ with either hypoxanthine or xanthine as the second substrate.

• Journal of Adhesion and Interface
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• v.3 no.2
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• pp.45-52
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• 2002

기존의 점착제 합성방법에서 탈피하여 용액형 점착제(Solution)의 장점과 입자형 점착제(Emulsion)의 장점을 동시에 보유한 NAD (Non-Aqueous Dispersion Polymer)를 합성하였다. NAD는 메탄올 분위기에서 6개월 이상의 분산 안정성을 유지하였다. NAD는 용액에서 입자형 고분자의 형태를 이루고 있음을 도공 공정에서 확인하였다. 또한 기존의 아크릴 점착제의 장점과 고무계점착제의 장점을 결합한 고분자량의 점착제, GP (Graft Polymer)를 합성하였다. GP는 자체가 매우 높은 분자량을 보유하여 가교제의 첨가 없이도 우수한 물성을 나타내었다. GP는 일반적으로 고 분자량의 고분자에서 나타나는 Weissenberg effect 현상을 나타내었다. 이들의 점착제로 응용시 각각의 물성을 비교하여 나타내었다.

• Journal of Electrochemical Science and Technology
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• v.5 no.1
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• pp.19-22
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• 2014

Here we report a highly sensitive and stable detection of $NAD^+$ and NADH by the electrode on which diaphorase (DI) is covalently immobilized in viologen polymer network. The network is prepared by the covalent formation of the structure by mixing propylamine viologen (PAV), poly(ethylene glycol)(400) diglycidyl ether (PEGDGE), an diaphorase (DI). The PAV/PEGDGE/DI modified electrode has the sensitivity of $0.02nA{\cdot}{\mu}M$ and the detection limit of $3{\mu}M$ with a response time of 2 s ($t_{90%}$) for NADH sensing.

• YAKHAK HOEJI
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• v.36 no.5
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• pp.469-473
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• 1992

Yeast alcohol dehydrogenase (YADH) has an acidic residue that interacts with the 2'- and 3'-hydroxyl groups of the adenosine ribose of the $NAD^+$ coenzyme. The acidic residue of Asp-223 (according to horse liver alcohol dehydrogenase amino acid sequence) is supposed to determine the coenzyme specificity for $NAD^+$ rather than $NADP^+$. We mutated Asp-223 to leucine and the mutant YADH was expressed in yeast and characterized for the coenzyme specificity. The turnover numbers of mutant enzyme for $NAD^+$ and ethanol were decreased 3.5- and 4.8-fold compared to wild-type enzyme, respectively. Contrastively, catalytic specificity for $NADP^+$ was increased 13-fold. As a result, the mutant YADH also employed $NADP^+$ as a coenzyme.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.199-204
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• 2011

This paper evaluates on the feasibility of MIL-STD-188-220 protocol as a medium access protocol over WNW(Wideband Network Waveform) by simulating and comparing with IEEE 802.11e-based protocol. WNW is newly designed waveform for next-generation broadband tactical communication system. This paper shows the feasibility of using the MIL-STD-188-220 protocol that shows better performance than IEEE 802.11e-based protocol on the particular environment.

• Biodesign
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• v.7 no.1
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• pp.24-27
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• 2019

Pnc1 converts nicotinamide to nicotinic acid to generate NAD⁺ through the Preiss-Handler pathway that is one of the NAD⁺-salvage pathway. By reducing levels of nicotinamide, an inhibitor of the NAD⁺-dependent histone deacetylase Sir2, yeast Pnc1 contributes gene silencing. In this study, to understand the structural features and molecular mechanism of nicotinamidase Pnc1, we overexpressed, purified, and crystallized the N-terminally His₆-tagged Pnc1 protein from Kluyveromyces lactis and obtained X-ray diffraction data at a resolution of 2.2 Å. The crystals of the K. lactis Pnc1 (KlPnc1) belonged to space group P2₁2₁2₁ with unit cell parameters a=38.5, b=77.3, c=83.3, and α=β=γ= 90°. There is one molecule in the asymmetric unit.