• BMB Reports
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• v.33 no.4
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• pp.321-325
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• 2000

Quinone reductase was purified to homogeneity from bovine liver by using ammonium sulfate fractionation, ionexchange chromatography, and gel filtration chromatography. The enzyme utilized either NADH or NADPH as the electron donor. The enzyme catalyzed the reduction of several quinones and other artificial electron acceptors. Furthermore, the enzyme catalyzed NAD(P)H-dependent reduction of azobenzene. The apparent Km for 1,4-benzoquinone and azobenzene was 1.64 mM and 0.524 mM, respectively. The reduction of azobenzene by quinone reductase was almost entirely inhibited by dicumarol or Cibacron blue 3GA, potent inhibitors of the mammalian quinone reductase. In the presence of 1.0${\mu}M$ Cibacron blue 3GA, azoreductase activity was lowered by 45%, and almost complete inhibition was seen above 2.0 ${\mu}M$ Cibacron blue 3GA.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.638-639
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• 2000

Quinone reductase was purified to electrophoretic homogeneity from bovine liver by using ammonium sulfate fractionation, ion-exchange chromatography, and gel filtration chromatography. The enzyme utilized either NADH or NADPH as the electron donor. The optimum pH of the enzyme was pH 8.5, and the activity of the enzyme was greatly inhibited by $Cu^{2+}$ and $Hg^{2+}$ ions, dicumarol and cibacron blue 3GA. The enzyme catalyzed the reduction of several quinones and other artificial electron acceptors. Furthermore, the enzyme catalyzed NAD(P)H-dependent reduction of azobenzene or 4-nitroso-N,N-dimethylaniline. The apparent $K_m$ for 1,4-benzoquinone, azobenzene, and 4-nitroso-N,N-dimethylaniline was 1.64mM, 0.524mM and 0.225mM, respectively. The reduction of azobenzene or 4-nitroso-N,N-dimethylaniline by quinone reductase was strongly inhibited by dicumarol or cibacron blue 3GA, potent inhibitors of quinone reductase.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.161-166
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• 2002

Bioremediation of trace metals in groundwater may require the manipulation of redox conditions via the injection of a carbon source. To simulate the numerous biogeochemical processes that will occur during the bioremediation of trace-metal-contaminated aquifers, a reactive transport model has been developed. The model consists of a set of coupled mass balance equations, accounting for advection, hydrodynamic dispersion, and a kinetic formulation of the biological or chemical transformations affecting an organic substrate, electron acceptors, corresponding reduced species, and trace metal contaminants of interest, uranium in this study. The redox conditions of the domain are characterized by estimating the pE, based on the concentrations of the dominant terminal electron acceptor and its corresponding reduced specie. This pE and the concentrations of relevant species we then used by a modified version of MINTEQA2, which calculates the speciation/sorption and precipitation/dissolution of the species of interest under equilibrium conditions. Kinetics of precipitation/dissolution processes are described as being proportional to the difference between the actual and calculated equilibrium concentration.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.415.1-415.1
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• 2014

Carrying out first-principles calculations, we study N-doped capped carbon nanotube (CNT) electrodes applied to DNA sequencing. While we obtain for the face-on nucleobase junction configurations a conventional conductance ordering where the largest signal results from guanine according to its high highest occupied molecular orbital (HOMO) level, we extract for the edge-on counterparts a distinct conductance ordering where the low-HOMO thymine provides the largest signal. The edge-on mode is shown to operate based on a novel molecular sensing mechanism that reflects the chemical connectivity between N-doped CNT caps that can act both as electron donors and electron acceptors and DNA functional groups that include the hyperconjugated thymine methyl group[1].

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.302-310
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• 2017

The morphological characteristics of granules developing in anaerobic-anoxic (An-Ax) and anaerobic-aerobic (An-Ox) sequencing batch reactors (SBRs) were examined. The granules developed in the both SBRs after 200 days of laboratory operation. The average diameters of the granules were $2.2{\pm}1.7mm$ in the An-Ax SBR and $0.4{\pm}0.3mm$ in the An-Ox SBR. To determine the possible factors affecting morphology of granules a comparative analysis of various operating conditions from reference data indicated that the availability and type of electron acceptors is a key factor determining the granulation process and granular morphology.

• Korean Journal of Microbiology
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• v.21 no.1
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• pp.27-35
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• 1983

The stoichiometry between the consumption of CO and $O_2$ and the production of $CO_2(2CO+O_2{\rightarrow}2CO_2)$) showed that Pseudomonas carboxydohydrogena grows as a typical aerobic CO oxidizer with CO. The optimal concentration of CO for growth was found to be 30% in gas mixture with air. The initial buffer concentration of the culture medium did not affect the growth of this bacterium. P. carboxydohydrogena is an obligate aerobe and dose not use nitrate as a terminal electron acceptor. The CO dehydrogenase is an inducible and soluble enzyme. The reaction rate and stability were maximal at pH7.5, and the Arrhenius plot revealed an activation energy of 37.7kJ/mol (9.0 Kcal/mol). The crude enzyme used methylene blue, thionin, and toluylene blue as electron acceptors for the oxidation of CO to $Co_2$ under anaerobic conditions. It was found that water must be the source of the second oxygen atom for CO oxidation.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.948-952
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• 2008

The molecular association of acceptors with electron donors is studied in the highly-polar solvent $CH_3CN$. Tetracyanoquinodimethane (TCNQ) forms a stable charge-transfer complex with donor molecules such as 4- aminobiphenyl (4-AB), benzidine (BD) and 2-aminobiphenyl (2-AB) with high association constants. The complexes of TCNQ with 4-AB or BD show new absorption bands at around 800 and 500 nm, which can be identified as reduced $TCNQ^{{\bullet}-}$ and $TCNQ^{2-}$ species, respectively. These bands grow quickly upon photoirradiation, implying that the charge-transfer complexes are easily formed in an excited state. Conversely, a small spectral manifestation of the charge transfer was observed in the case of 2-AB complex. It is demonstrated that the structural orientation between the geminate ion pairs could play an important role in building a stable complex.

• Bulletin of the Korean Chemical Society
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• v.20 no.10
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• pp.1172-1176
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• 1999

Nucleophilic substitution reaction of Y-benzyl bromide with X-pyridines are investigated in DMSO at 45.0℃. Biphasic rate dependence is observed on varying the substituents in the substrate (Y) as well as in the nucleophile (X). The two well-defined straight lines in the Hammett (ρy) and Bronsted ( βx) plots are interpreted to indicate the changes in transition-state structure, a decrease in bond cleavage as the substituent on the substrate is changed from electron-donors ( ρy < 0) to electron-acceptors ( ρy > 0), and an increase in the extent of bond formation with the corresponding changes of the substituent on the pyridine. A Jencks' type analysis of separate polar (ρ) and resonance (ρr) effects can also be accounted for by the change of the transition-state structure, not by the variable combination of polar and resonance effects.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.368-371
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• 2003

Accidental release of petroleum products from underground storage tank(USTs) is one of the most common causes of groundwater contamination. BTEX is the major components of fuel oils, which are hazardous substances regulated by many nations. In addition to BTEX, other gasoline consituents such as MTBE(methyl-t-buthyl ether), anphthalene are also toxic to humans. Natual attenuation processes include physic, chemical, and biological trasformation. Aerobic and anaerobic biodegradation are believed to be the major processes that account for both containment of the petroleum-hydrocarbon plum and reduction of the contaminant concentrations. Aerobic bioremediation has been highly effective in the remediation of many fuel releases. However, Bioremediation of aromatic hydrocarbons in groundwater and sediments is ofen limited by the inability to provide sufficient oxygen to the contaminated zones due to the low water solubility of oxygen. Anaerobic processes refer to a variety of biodegradation mechanisms that use nitrate, ferric iron, sulfate, and carbon dioxide as terminal electron accepters. The objectives of this study was to conduct laboratory-scale microcosm studies in assessing enhanced bioremediation potential of BTEX and MTBE under various electron accepters(aerobic, nitrate, ferric iron, sulfate) in contaminated Soil. these results suggest that, presents evidence and a variety pattern of the biological removal of aromatic compounds under enhanced nitrate-, Fe(III)-, sulfate-reducing conditions.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3211-3217
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• 2013

Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations have been employed to investigate the molecular structures and absorption spectra of three D-${\pi}$-A-type organic dyes (C1-1, D5 and TH208) containing identical ${\pi}$-spacers and electron acceptors, but different aromatic amine electron-donating groups (tetrahydroquinoline, triphenylamine and phenothiazine). The coplanar geometries indicate that the strong conjugation is formed in the dyes. The electronic structures suggest that the intramolecular charge transfer from the donor to the acceptor occurs, and the electron-donating ability of tetrahydroquinoline is stronger than those of triphenylamine and phenothiazine. The computed orbital energy levels of these dyes confirm that the electrons could be injected from the excited dyes to the semiconductor conduction band and the oxidized dyes could be reduced effectively by electrolyte. The TD-DFT results show that the CAM-B3LYP/6-31+G(d, p) is suitable for calculating the absorption spectra. The first absorption band for these dyes is assigned to the HOMO${\rightarrow}$LUMO and HOMO-1${\rightarrow}$LUMO transitions.