• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.126.1-126
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• 1998

• Proceedings of the Microbiological Society of Korea Conference
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• 2002.10a
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• pp.129-131
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• 2002

• Journal of the Korean Chemical Society
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• v.44 no.1
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• pp.4-9
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• 2000

We investigated the self-association and protonation state of norfloxacin, a member of quinokme antibiotics, using electric absorption and potentiom,etric titration. Both nitrogen at the piperazine ring and carboxylic acid were protonated at a low pH (cationic norfloxacin), and deprotonated at a high pH (anionic norfloxacin). In the intermediate pH range, a neutral species was dominant with the possibility of forming a zwitter ion. We also observed that nortloxacin molecules can be sracked to form a dimer at an intermediate pH, The equilibrium constant of the norfloxacin-DNA complex formation, which was measured by Stem-Volmermethod, increases as the pH of the system is lowered. This observation indicates that it is the cationic nortloxacin that forms a complex with DNA among various norfloxacin species in aqueous solution.

• BMB Reports
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• v.38 no.4
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• pp.474-480
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• 2005

Curcumin, a major active component of turmeric, has been identified as an inhibitor of the transcriptional activity of activator protein-1 (AP-1). Recently, it was also found that curcumin and synthetic curcumin derivatives can inhibit the binding of Jun-Fos, which are the members of the AP-1 family, to DNA. However, the mechanism of this inhibition by curcumin and its derivatives was not disclosed. Since the binding of Jun-Fos dimer to DNA can be modulated by redox control involving conserved cysteine residues, we studied whether curcumin and its derivatives inhibit Jun-Fos DNA binding activity via these residues. However, the inhibitory mechanism of curcumin and its derivatives, unlike that of other Jun-Fos inhibitors, was found to be independent of these conserved cysteine residues. In addition, we investigated whether curcumin derivatives can inhibit AP-1 transcriptional activity in vivo using a luciferase assay. We found that, among the curcumin derivatives examined, only inhibitors shown to inhibit the binding of Jun-Fos to DNA by Electrophoretic Mobility Shift Assay (EMSA) inhibited AP-1 transcriptional activity in vivo. Moreover, RT-PCR revealed that curcumin derivatives, like curcumin, downregulated c-jun mRNA in JB6 cells. These results suggest that the suppression of the formation of DNA-Jun-Fos complex is the main cause of reduced AP-1 transcriptional activity by curcuminoids, and that EMSA is a suitable tool for identifying inhibitors of transcriptional activation.

• Archives of Pharmacal Research
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• v.25 no.2
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• pp.143-150
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• 2002

Fluorescent probes bound to DNA typically display nanosecond decay times and reveal only nanosecond motions. We extend the time range of measurable DNA dynamics using $[Ru(pby)_2(dppz)]^{2+}$ (bpy=2.2'-bipyridine, dppz=dipyrido[3,2-a2',3'-c]phenazine) (RuBD) which displays a mean lifetime near 90 ns. To test the usefulness of RuBD as a probe for diffusive processes in calf thymus DNA, we compared the efficiencies of fluorescence resonance energy transfer (FRET) using three donors which display lifetimes near 5 ns for acridine orange (AO), 22 ns for ethidum bromide (EB) and 92 ns for RuBD, with nile blue (NB) as the acceptor. The F rster distances for AO-NB, EB-NB and RuBD-NB donor-acceptor pairs were 42.3, 52.3, and $30.6{\;}{\AA}$, respectively. All three donors showed dramatic decreases in fluorescence intensities and more rapid intensity decays with increasing NB concentrations. The intensity decays of AO and EB in the presence of varying concentrations of NB were satisfactorily described by the one-dimensional FRET model without diffusion (Blumen and Manz, 1979). In the case of the long-lifetime donor RuBD, the experimental phase and modulation somewhat deviated from the recovered values computed from this model. The recovered NB concentrations and FRET efficiencies from the model were slightly larger than the expected values, however, the recovered and expected values did not show a significant difference. Thus, it is suggested that the lifetime of RuBD is too short to measure diffusive processes in calf thymus DNA.

• Journal of the Korean Magnetic Resonance Society
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• v.21 no.3
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• pp.90-95
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• 2017

The Z-DNA domain of human ADAR1 ($Z{\alpha}_{ADAR1}$) produces B-Z junction DNA through preferential binding to the CG-repeat segment and destabilizing the neighboring AT-rich region. However, this study could not answer the question of how many base-pairs in AT-rich region are destabilized by binding of $Z{\alpha}_{ADAR1}$. Thus, we have performed NMR experiments of $Z{\alpha}_{ADAR1}$ to the longer DNA duplex containing an 8-base-paired (8-bp) CG-repeat segment and a 12-bp AT-rich region. This study revealed that $Z{\alpha}_{ADAR1}$ preferentially binds to the CG-repeat segment rather than AT-rich region in a long DNA and then destabilizes at least 6 base-pairs in the neighboring AT-rich region for efficient B-Z transition of the CG-repeat segment.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.524-526
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• 1999

In the construction of successful fuzzy models and/or controllers for nonlinear systems, the identification of a good fuzzy inference system is an important yet difficult problem, which is traditionally accomplished by a time-consuming trial-and-error process. In this paper, we propose a systematic identification procedure for complex multi-input single-output nonlinear systems with DNA coding method. A DNA coding method is optimization algorithm based on biological DNA as conventional genetic algorithms(GAs) are. The strings in the DNA coding method are variable-length strings, while standard GAs work with a fixed-length coding scheme. the DNA coding method is well suited to learning because it allows a flexible representation of a fuzzy inference system. We also propose a new coding method fur applying the DNA coding method to the identification of fuzzy models. This coding scheme can effectively represent the zero-order Takagi-Sugeno(TS) fuzzy model. To acquire optimal TS fuzzy model with higher accuracy and economical size, we use the DNA coding method to optimize the parameters and the number of fuzzy inference system. In order to demonstrate the superiority and efficiency of the proposed scheme, we finally show its application to a Duffing-forced oscillation system.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.254-254
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• 2006

The sensitivity of plasmid DNA (pDNA) to S1 nuclease, an enzyme to cleave a single-strand DNA, was dramatically modulated through a supramolecular assembly (polyion complex micelle) with a synthetic block copolymer, poly(ethylene glycol)-b-poly(L-lysine) (PEG-PLL). The pDNA condensed in stoichiometric charge ratio was cleaved into 7 fragments each being 10/12, 9/12, 8/12, 6/12, 4/12, 3/12, and 2/12 of the original DNA length, on the other hand, the pDNA condensed in higher charge ratios (>4), were digested into non-specific manner. Condensation of the pDNA was investigated from two viewpoints that how does the rigid DNA molecules fold and condense and how does the condensation influence their biological activity.

• Korean Journal of Cognitive Science
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• v.14 no.2
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• pp.15-25
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• 2003

The Monkey and Banana Problem is an example commonly used for illustrating simple problem solving. It can be solved by conventional approaches, but this requires a procedural aspect when inferences are processed, and this fact works as a limitation condition in solving complex problems. However, if we use DNA computing methods which are naturally able to realize massive parallel processing. the Monkey and Banana Problem can be solved effectively without weakening the fundamental aims above. In this paper, we design a method of representing the problem using DNA molecules, and show that various solutions are generated through computer-simulations based on the design. The simulation results are obviously interesting in that these are contrary to the fact that the Prolog program for the Monkey and Banana Problem, which was implemented from the conventional point of view, gives us only one optimal solution. That is, DNA computing overcomes the limitations of conventional approaches.

• Journal of Pharmaceutical Investigation
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• v.26 no.4
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• pp.291-297
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• 1996

Liposomes of $pSV-{\beta}-Galactosidase$ vector plasmid DNA with various lipid composition were prepared by the thin-film method. Size distribution, shape and the efficiency of plasmid DNA encapsulation were investigated. Effect of sonication time on the plasmid DNA entrapment in liposomes and stability at $4^{\circ}C$ were also examined. Sizes of neutral liposomes were about 100-200 nm and above $1\;{mu}m$, and those of cationic liposomes were about 400-600 nm and above $1\;{mu}m$. Shapes of liposomes entrapped plasmid DNA were spherical. Proper sonication time for better entrapment was below 15 minutes and stability at $4^{\circ}C$ was decreased rapidly after 1 day. Plasmid DNA entrapments of complex liposomes of various lipids were higher than those of liposomes made from one sort of lipid. Plasmid DNA entrapments of cationic liposomes were higher than those of neutral liposomes.