• 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.

• 한국전기화학회:학술대회논문집
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• 2001.10a
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• pp.13-13
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• 2001

• Bulletin of the Korean Chemical Society
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• v.11 no.1
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• pp.71-72
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• 1990

• Journal of Microbiology and Biotechnology
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• v.14 no.5
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• pp.919-923
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• 2004

The sk10 isolated from kimchi was identified as W. kimchii on the basis of l6s-rDNA sequencing. Studies were made to analyze the metabolic flux shift of the sk10 on glucose under aerobic growth conditions. The sk10 produced 38.2 mM acetate, 16.3 mM ethanol, and 33.2 mM lactate under aerobic conditions, but 2.4 mM acetate, 48.0 mM ethanol, and 44.1 mM lactate under anaerobic conditions. The NADH peroxidase (NADH-dependent hydrogen peroxidase) activity of sk10 grown under aerobic conditions was 11 times higher than that under anaerobic conditions. Under the low ratio of $NADH/NAD^+$, the metabolic flux toward lactate and ethanol was shifted to the flux through acetate kinase without NADH oxidation. The kinds of enzymes and metabolites of sk10 were close to those in the pathway of Leuconostoc sp., but the metabolites produced under aerobic growth conditions were different from those of Leuconostoc sp. The stoichiometric balance calculated using the concentrations of metabolites and substrate was about 97%, coincident with the theoretical values under both aerobic and anaerobic conditions. From these results, it was concluded that the metabolic flux of W. kimchii sk10 was partially shifted from lactate and ethanol to acetate under aerobic conditions only.

• Journal of Microbiology and Biotechnology
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• v.14 no.3
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• pp.540-546
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• 2004

We deviced a new graphite-Mn(II) electrode and found that the modified electrode with Mn(II) can catalyze NADH oxidation and $NAD^+$ reduction coupled to electricity production and consumption as oxidizing agent and reducing power, respectively. In fuel cell with graphite-Mn(II) anode and graphite-Fe(III) cathode, the electricity of 1.5 coulomb (A x s) was produced from NADH which was electrochemically reduced by the graphite-Mn(II) electrode. When the initial concentrations of pyruvate and acetaldehyde were adjusted to 40 mM and 200 mM, respectively, about 25 mM lactate and 35 mM ethanol were produced from 40 mM pyruvate and 200 mM acetaldehyde, respectively, by catalysis of ADH and LDH in the electrochemical reactor with $NAD^+$ as cofactor and electricity as reducing power. By using this new electrode with catalytic function, the bioelectrocatalysts are engineered; namely, oxidoreductase (e.g., lactate dehydrogenase) and $NAD^+$ can function for biotransformation without electron mediator and second oxidoreductase for $NAD^+$/NADH recycling.

• Journal of the Korean Chemical Society
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• v.48 no.2
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• pp.151-155
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• 2004

The self-assembled mololayers(SAMs)were prepared with cysteine(cys) and subsequently coupled with dopamine(dopa) containing quinone functionality on the gold modified electrodes. The SAMs annealed in ethanol for 6 hours gave a better shaped cyclic voltammogram which had a 0.28 V of formal potential and same redox potential in 0.1M phosphate buffer(pH=7.10). The electrodes were employed to determine concentration of HADH with the result that calibration curve exhibited an excellent correlation(${\geq}$ 0.993) for the concentrations ranging up to 5.0${\times}10^{-4}$ M.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.160.3-161
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• 2003

Aldehyde and active form of free oxygen produced in alcohol metabolism in liver are the cause of liver cell damage. The main system of alcohol metabolism is composed of alcohol dehydrogenase(ADH), aldehyde dehydrogenase(ALDH) and cytochrome P4502E1. Alcohol dehydrogenase is reversible in alcohol metabolism. To block the backward reaction and enhance alcohol oxidation, acetaldehyde trapping agents were assayed. The assay was carried out by measuring decreasing NADH at 340nm, using acetaldcehyde and NADH as substrate and coenzyme respectively. (omitted)

• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.668-673
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• 2012

Biohydrogen production from organic wastewater by anaerobically activated sludge fermentation has already been extensively investigated, and it is known that hydrogen can be produced by glucose fermentation through three metabolic pathways, including the oxidative decarboxylation of pyruvic acid to acetyl-CoA, oxidation of NADH to $NAD^+$, and acetogenesis by hydrogen-producing acetogens. However, the exact or dominant pathways of hydrogen production in the anaerobically activated sludge fermentation process have not yet been identified. Thus, a continuous stirred-tank reactor (CSTR) was introduced and a specifically acclimated acidogenic fermentative microflora obtained under certain operation conditions. The hydrogen production activity and potential hydrogen-producing pathways in the acidogenic fermentative microflora were then investigated using batch cultures in Erlenmeyer flasks with a working volume of 500 ml. Based on an initial glucose concentration of 10 g/l, pH 6.0, and a biomass of 1.01 g/l of a mixed liquid volatile suspended solid (MLVSS), 247.7 ml of hydrogen was obtained after a 68 h cultivation period at $35{\pm}1^{\circ}C$. Further tests indicated that 69% of the hydrogen was produced from the oxidative decarboxylation of pyruvic acid, whereas the remaining 31% was from the oxidation of NADH to $NAD^+$. There were no hydrogen-producing acetogens or they were unable to work effectively in the anaerobically activated sludge with a hydraulic retention time (HRT) of less than 8 h.

• Environmental Mutagens and Carcinogens
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• v.16 no.1
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• pp.13-18
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• 1996

One mechanism of free-radical production by ethanol is suggested to be through the intracellular conversion of XDH to XO by increased ratio of NADH to NAD. The major mechanism for physiological compensation of cytosolic NADH/NAD balance is the malate/aspartate shutfie. Therefore, it is important to develop the method to improve the efficiency of malate/aspartate shuttle in ethanol metabolism. In the present study, various amino acids and organic acid involved in the shuttle were tested for their functional efficiency in modulating shuttle in the ethanol-perfused rat liver. The rate of ethanol oxidation in the liver perfused with aspartate alone or aspartate in combination with pyruvate, respectively, was increased by about 10% compared to control liver, but not in the tissues perfused with glummate, cysteine or pyruvate alone. Though glummate, cysteine and pyravate did not affect the ethanol oxidation significanfiy, they showed some suppresive effect on the ethanol-induced radical generation monitored by protein carbonylation analysis. Among the tested components, aspartate is confirmed to be the most efficient as a metabolic regulator for both ethanol oxidation and ethanol-induced oxidative stress in our perfusion system. These effects of aspartate would result from NAD recycling by its supplementation through the coupled aspartate aminotransferase/malate dehydrogenase reactions and the malate-aspartate shuttle.

• Korean Journal of Plant Tissue Culture
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• v.25 no.4
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• pp.277-282
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• 1998

Whereas cationic extracellular peroxidases (PODs) were observed in the suspension cultures of rose (Rosa sp. L. cv Pual's scarlet) grown under normal conditions, new anionic isozymes were induced within 24 hr by the treatment of low host-specific elicitor (10 mg glucan/L media) prepared from yeast cell wall. Prominent anionic (pI 6.1) and cationic POD (pI 8.4) were purified and characterized to understand the physiological role of the enzymes. Both enzymes were purified (ca.200 fold) by the ammonium sulfate precipitation, ion exchange chromate-graphy and gel filtration chromatography. The Km values of the purified anionic POD for ferulic acid and $\textrm{H}_2\textrm{O}_2$ were 4.64 mM and 0.72 mM, whereas those of the cationic POD were 1.38 mM and 0.48 mM, respetively. The activity of the anionic POD as NADH oxidase was twice higher than that of cationic POD. The NADH oxidation in the anionic POD fraction was inhibited by 60% on the addition of 0.1 mM coniferyl alcohol, while that in the cationic fraction was inhibited by 15%.