• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2000.10a
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• pp.181-188
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• 2000

The electrocatalytic reduction of NAD$^{＋}$ using diaphorase was studied. methyl viologen (MV$^{2＋}$) mediator between an electrode and the enzyme. Steady-state currents could be obtained under the conditions of slow scan rate, low MV$^{2＋}$concentration, and high NAD$^{＋}$ concentration as the electrode reaction was converted to an electrochemical-catalytic (EC') reaction. The biomecular rate constant for the reaction of the reduced methyl viologen with the oxidized diaphorase was estimated as 7.5$\times$10$^3$M$^{-1}$ s$^{-1}$ from the slope of the current versus [MV$^{2＋}$] plot. And the optimal concentrations of diaphorase, MV$^{2＋}$ and NAD$^{＋}$ in the mediated electrocatalytic reduction of NAD$^{＋}$ were decided by applying the cyclic voltammetry. The optimal concentrations of the species were obtained by finding the conditions which gave the highest and steady-state current at a gold-amalgam electrode. The highest and steady-state catalytic current was achieved under the conditions of 1.5 U/ml diaphorase, 0.2 mM MV$^{2＋}$, and 4.8 mM NAD$^{＋}$ at the scan rate of 2 mV s$^{-1}$ , suggesting that the rate of the electrocatalytic reation is the higest under the former conditions. The electrochemical procedure under the conditions of 1.5 U/ml diaphorase,0.2 mM MV$^{2＋}$, and 4.8 mM NAD$^{＋}$ was used favorably to drive an enzymatic reduction of pyruvate to D-lactate.

• BMB Reports
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• v.40 no.6
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• pp.952-958
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• 2007

We isolated many genes induced from pepper cDNA microarray data following their infection with the soybean pustule pathogen Xanthomonas axonopodis pv. glycines 8ra. A full-length cDNA clone of the Capsicum annuum ankyrin-repeat domain $C_3H_1$ zinc finger protein (CaKR1) was identified in a chili pepper using the expressed sequence tag (EST) database. The deduced amino acid sequence of CaKR1 showed a significant sequence similarity (46%) to the ankyrin-repeat protein in very diverse family of proteins of Arabidopsis. The gene was induced in response to various biotic and abiotic stresses in the pepper leaves, as well as by an incompatible pathogen, such as salicylic acid (SA) and ethephon. CaKR1 expression was highest in the root and flower, and its expression was induced by treatment with agents such as NaCl and methyl viologen, as well as by cold stresses. These results showed that CaKR1 fusion with soluble, modified green fluorescent protein (smGFP) was localized to the cytosol in Arabidopsis protoplasts, suggesting that CaKR1 might be involved in responses to both biotic and abiotic stresses in pepper plants.

• Journal of Plant Biotechnology
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• v.31 no.2
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• pp.109-113
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• 2004

In order to develop transgenic potato plants with enhanced tolerance to multiple stress, we constructed the transformation vector expressing both superoxide dismutase and ascorbate peroxidase genes in chloroplasts under the control of a stress-inducible SWPA2 promoter. Transgenic potato plants (cv. Superior and Atlantic) were generated using an Agrobacterium-mediated transformation system. Transgenic potato plants were regenerated on MS medium containing 100mg/L kanamycin. Genomic Southern blot analysis confirmed the incorporation of foreign genes into the potato genome. When potato leaf discs were subjected to methyl viologen (MV) at 10 $\mu$M, transgenic plants showed higher tolerance than non-transgenic or vector-transformed plants. To further study we selected the transgenic plant lines with enhanced tolerance against MV. These plants will be used for further analysis of stress-tolerance to multiple environmental stresses.

• Molecules and Cells
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• v.25 no.3
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• pp.368-375
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• 2008

Approximately 120 UDP-glycosyltransferases (UGTs), which are classified into 14 distinct groups (A to N), have been annotated in the Arabidopsis genome. UGTs catalyze the transfer of sugars to various acceptor molecules including flavonoids. Previously, UGT71C1 was shown to glycosylate the 3-OH of hydroxycinnamates and flavonoids in vitro. Such secondary metabolites are known to play important roles in plant growth and development. To help define the role of UGT71C1 in planta, we investigated its expression patterns, and isolated and characterized a loss-of-function mutation in the UGT71C1 gene (named ugt71c1-1). Our analyses by quantitative real-time reverse transcriptase polymerase chain reaction (qRT-PCR), microarray data mining, and histochemical detection of GUS activity driven by the UGT71C1 promoter region, revealed the tissue-specific expression patterns of UGT71C1 with highest expression in roots. Interestingly, upon treatment with methyl viologen (MV, paraquat), ugt71c1-1 plants displayed enhanced resistance to oxidative stress, and ROS scavenging activity was higher than normal. Metabolite profiling revealed that the levels of two major glycosides of quercetin and kaempferol were reduced in ugt71c1-1 plants. In addition, when exposed to MV-induced oxidative stress, eight representative ROS response genes were expressed at lower levels in ugt71c1-1 plants, indicating that ugt71c1-1 probably has higher non-enzymatic antioxidant activity. Taken together, our results indicate that ugt71c1-1 has increased resistance to oxidative stress, suggesting that UGT71C1 plays a role in some glycosylation pathways affecting secondary metabolites such as flavonoids in response to oxidative stress.

• Bulletin of the Korean Chemical Society
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• v.6 no.5
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• pp.287-291
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• 1985

The addition of poly(styrenesulfonate) (PSS) to $Ru(bpy)_3^{2+}$ solutions shifted the emission peak by 3 nm to red, and increased emission intensity by 1.8 times. By contrast, poly(vinylsulfonate) (PVS) had little effect on the fluorescence spectrum. The effects of PSS on the spectral properties of $Ru(bpy)_3^{2+}$, were attributed to the presence of a hydrophobic phenyl group in PSS, which interact with $Ru(bpy)_3^{2+}$ by, at least in part, hydrophobic effect. The binding constant of $Ru(bpy)_3^{2+}$ to PSS in 0.1 M NaCl was $6{\times}10^4\;M^{-1}$, and this value was about $10^3$ times higher than those of methyl viologen ($MV^{2+}$) and $Cu^{2+}$. The Stern-Volmer constants of emission quenching of $Ru(bpy)_3^{2+}$ by $MV^{2+}$ and $Cu^{2+}$ in 0.1 M NaCl solutions were 426 and 40 $M^{-1}$, which correspond to second order rate constants($k_q$) of $1.1{\times}10^9\;and\; 1.0{\times}10^8\;M^{-1}s^{-1}$, respectively. The presence of PSS enhanced $K_{SV's}\;by\;{\sim}50$ times, whereas PVS increased the values only 1-4 times. The large enhancing effect of PSS, despite of lower charge density than PVS, was explained in terms of longer life-time of photoexcited $Ru(bpy)_3^{2+}$ bound to PSS and strong association of $Ru(bpy)_3^{2+}$ to PSS due to a specific interaction involving hydrophobic effect. The variation of $K_{SV's}$ on the concentrations of PVS and PSS were also investigated for $Ru(bpy)_3^{2+}-MV^{2+}\;and \;Ru(bpy)_3^{2+}-Cu^{2+}$ photoredox systems.

• Korean Journal of Materials Research
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• v.31 no.3
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• pp.132-138
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• 2021

Electrochromic devices (ECDs) have been drawing great attention due to their high color contrast, low power consumption, and memory effect, and can be used in smart windows, automatic dimming mirrors, and information display devices. As with other electronic devices such as LEDs (light emitting diodes), solar cells, and transistors, the mechanical flexibility of ECDs is one of the most important issue for their potential applications. In this paper, we report on flexible ECDs (f-ECDs) fabricated using an all-in-one EC gel, which is a mixture of electrolyte and EC material. The f-ECDs are compared with rigid ECDs (r-ECDs) on ITO glass substrate in terms of color contrast, coloration efficiency, and switching speed. It is confirmed that the f-ECDs embedding all-in-one gel show strong blue absorption and have competitive EC performance. Repetitive bending tests show a degradation of electrochromic performance, which must be improved using an optimized device fabrication process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.05a
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• pp.77-80
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• 1995

Enhancing the electrical conductivity of the ultrathin organic films using Langmuir-Blodget technique is important step for the developement of molecular electronic device. The Octadecylviologen-TCNQ was synthesized with Octadecylviologen-Bromide an Lithium TCNQ Sine Octadecylviologen-TCNQ has two TCNQ snion radicals, the conductivity of LB film is expected to increase. The $\pi$-A isotherm showed that the limiting area was 150${\AA}$$\^$2/ molecule and the silid-like transition surface pressure was 25 mN/m. The electronic transition of the TNCNQ anion radical was observed at 400 nm. Intermolecular charge transfer absorption was observed at 600nm and 850~1050 nm which ay resulted from the TCNQ anion radical dimer formation. The electrical conductivity of the viologen -TCNQ LB film was 10$\^$-6/cm This values was 100 times higher than that of the quinolinium-TCNQ and pyridinium-TCNQ LB films.

• Rapid Communication in Photoscience
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• v.3 no.4
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• pp.67-69
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• 2014

Bis(2-thienyl)-diketopyrrolopyrrole having two $Zn^{II}$-cylcens (DPPCy) was synthesized. DPP-aggregates were constructed by self-organization of DPPCy and $dT_n$-DNAs. In the presence of L-ascorbic acid as an electron sacrifice reagent, the DPP aggregates immobilized on a gold electrode exhibit good anodic photocurrent responses as well as cathodic photocurrent responses in the presence of methyl viologen. The anodic photocurrent responses depend on the DNA lengths because of the formation of uniform DPP-aggregates corresponding to the DNA lengths. The present results show that photocurrent responses of the DPP-aggregates can be controlled by DNA lengths and electron sacrifice reagents.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.628-628
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• 2013

Graphene, a single layer of graphite, has raised extensive interest in a wide scientific community for its extraordinary thermal, mechanical, electrical and other properties [1,2]. However, because of zero-band gap of graphene, it is difficult to apply for electronic applications. To overcome this problem, chemical doping is one of way to opening grahene bandgap. According to experimental results, by changing doping concentration and doping time, it is possible to control work function of graphene. We can obtain results through raman spectroscopy, UPS, Sheet resistance. Moreover, electronic properties of doped graphene were studied by making field effect transistors. We were able to control the doping concentration, dirac point of graphene and work function of graphene by formng n-type, p-type doping materials. In this research, the chemicals of diazonium salts, viologen, etc. were used for extrinsic doping.

• BMB Reports
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• v.41 no.1
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• pp.86-91
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• 2008

The full-length cDNA of CaAbsi1 encodes a presumptive protein of 134 amino acid residues that has homology to a putative zinc finger protein in its C-terminus. The deduced amino acid sequence has 50% homology to Oryza sativa NP001049-274, the function of which is unknown. Expression of CaAbsi1 was reduced in response to inoculation of non-host pathogens. On the other hand it was induced one hour after exposure to high concentrations of NaCl or mannitol, and six hours after transfer to low temperature. Induction also occurred in response to oxidative stress, methyl viologen, hydrogen peroxide and abscisic acid. Our results suggest that CaAbsi1 plays a role in multiple responses to wounding and abiotic stresses.