• Applied Biological Chemistry
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• v.42 no.4
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• pp.330-335
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• 1999

Pentachlorophenol(PCP), which is very persistent in soil and water environment, was tried to detoxify with oxidoreductive catalysts(peroxidase, laccase, tyrosinase and birnessite). To find out detoxification of PCP, the transformation of PCP through oxidative coupling was investigated in the presence of various oxidoreductive catalysts. PCP incubated with peroxidase was significantly transformed, however, in case of tyrosinase, the transformation was negligible. Using peroxidase, the optimal reaction condition was pH 5.6 and $16^{\circ}C$. The transformation of PCP was very fast in initiation step until 30 min but, that was not observed after 180 min. The transformation of PCP was increased by increasing peroacidase amount. When the effect of humic monomer was investigated as co-substrate on the transformation of PCP, the transformation of PCP was mostly decreased in the incubation with peroxidase, laccase, and birnessite. The transformation of PCP, however, was slightly increased by the incubation with tyrosinase in the presence of humic monomers as co-substrate, except catechol. On the basis of the results obtained, it may be suggested that PCP is able to be effectively detoxified through oxidative coupling mediated with oxidoreductive catalysts.

• Journal of Environmental Health Sciences
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• v.31 no.1
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• pp.61-65
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• 2005

The oxidative transformation of triclosan with laccase from Trametes versicolor was conducted in a closed, temperature controlled system containing phosphate buffer for pH control. The optimum pH for triclosan transformation showed about 5. Despite the observation that elevated temperatures tended to inactivate the enzyme, increased transformation of triclosan was observed up to $50^{\circ}C$. Of the mediators studied, ABTS was most successful at enhancing triclosan transformation. About 80% of the toxicity of the initial mixture was reduced after the enzymatic treatment. In the presence of 1.0 mM of anions such as sulfite, sulfide, and cyanide, triclosan transformation was greatly inhibited. Chloride and fluoride ions exhibited inhibition of triclosan transformation at 25 mM. Ferric ion substantially inhibited triclosan transformation at 1.0 mM.

• Applied Biological Chemistry
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• v.41 no.5
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• pp.384-389
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• 1998

The herbicide propanil and its metabolite, DCA were incubated with oxidative catalysts in the presence or absence of humic monomers to evaluate the incorporation of them into humic substances. Propanil and DCA underwent little or no transformation by oxidatve catalysts in the absence of humic monomers. In the presence of humic monomers, the most effective co-substrate for transformation of propanil was syringic acid by laccase and HRP, that of DCA was catechol by laccase and HRP, and protocatechuic acid by birnessite. The transformation of DCA was the highest when it was incubated with catechol at pH 8.0 during 24 hrs by laccase, and with catechol at pH 3.0 during 2 hrs by HRP, and with protocatechuic acid at pH 5.0 during 2 hrs by birnessite. The DCA transformation increased with increasing concentration of humic monomers. The transformation of DCA was increased with about 5 times when it was incubated with lactase and birnessite together than lactase alone, but that of it was not effected when it was incubated with HRP and birnessite together. When DCA was incubated with dissolved organic carbon in the presence of oxidative catalysts, the transformation of it was not increased by laccase and birnessite but increased by HRP.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.73-80
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• 2015

An investigation on the removals of tetracycline (TTC), which is a family of antibiotics widely founded in the environment, from the aqueous solution by birnessite(${\delta}-MnO_2$)-mediated oxidative transformation was described. This study also examined the potential effect of the naturally occurring substances, humic acid (HA) on the oxidative transformation. The experiment was carried out in various conditions (reaction time, Mn oxide loadings, pH) and in the presence of HA as a batch test. The removals of TTC followed pseudo-first order reactions, and rate constants (k, $hr^{-1}$) for the removals of TTC were constantly increased with decreasing pH from 0.98 (pH 9) to 2.97 (pH 3). The rate constants also increased about 1.3 times when the birnessite loading increased from 1 to 2 g/L. Presence of HA (5 mg-C/L, at $pH{\geq}6$) caused some enhancement in the removals of TTC as compared to the control, and also showed the removal efficiencies of TTC in the birnessite mediated systems (TTC=0.25 mM, ${\delta}-MnO_2=2.0g/L$, pH 6) increased with increasing HA concentrations (1~10 mg-C/L). The results obtained from the oxidative transformation of TTC and the effect of HA were discussed in terms of reaction characteristics and mechanism.

• Korean Journal of Environmental Agriculture
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• v.17 no.3
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• pp.239-245
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• 1998

To investigate the formation of bound residue with soil organic materials by oxidative coupling, nitroaromatics and their reduced metabolites, the insecticide parathion and the herbicide asulam were incubated with oxidoreductase, laccase or horseradish peroxidase, in the presence or absence of humic monomers. Most of aminotoluenes and amino-nitrophenols were completely transformed while most of nitrotoluenes and nitrophenols remained unchanged by a lactase or horseradish peroxidase in the presence or absence of humic monomers. Amino-nitrotoluenes were not transformed without humic monomers, but the addition of various humic monomers caused a considerable difference in the transformation of amino-nitrotoluenes by a lactase or horseradish peroxidase. Amino-nitrotoluenes were most transformed in the presence of catechol, syringaldehyde and protocatechuic acid. The insecticide parathion with nitro group and its metabolite were not mostly transformed in the presence or absence of humic monomers. The herbicide asulam with amino group remained unchanged without humic monomers as well, but the stimulating effect on the transformation of asulam was caused by the addition of catechol, syringaldehyde, protocatechuic acid or caffeic acid with a lactase.

• Journal of Environmental Health Sciences
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• v.33 no.1 s.94
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• pp.63-67
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• 2007

Laccase catalyzes the oxidation and polymerization of aromatic compounds in the presence of molecular oxygen. The oxidative transformation of chlorophene with laccase was conducted in a closed, temperature controlled system. The optimal pH for transformation of chlorophene was proven to be about 5-6. As the temperature rose up to $55^{\circ}C$, the transformation of chlorophene increased. The chlorophene transformation was not enhanced in the presence of soluble polymers. The toxicity of the reaction mixture was increased two times than that of initial reaction mixture after the enzymatic treatment. ABTS has enhanced chlorophene transformation at 0.1 mM and showed negative linear relationship with residual chlorophene by the reaction.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.147-152
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• 2004

Aerobic cometabolism of cis-1,2-dichloroethylene (c-DCE) and c-DCE epoxide by a butane-grown mixed culture was evaluated. Transformation of c-DCE resulted in the concomitant generation of c-DCE epoxide. Chloride release studies showed nearly complete oxidative dechlorination of c-DCE (approximately 75%). Mass spectrometry confirmed tile presence of a compound with mass-to-charge-fragment ratios of 112, 83, 48, and 35. The values are in agreement with the spectra of a chemically synthesized c-DCE epoxide. Some evidences indicating the involvement of the monooxygenase in the transformation of c-DCE epoxide are: 1) $O_2$ requirement for c-DCE transformation and butane degradation; 2) butane inhibition on c-DCE transformation and vice versa; 3) the inactivation of c-DCE and c-DCE epoxide transformations by acetylene (a known monooxygenase inactivator); and 4) tire inhibition of c-DCE epoxide transformation by c-DCE.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.43-46
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• 2004

Explosive chemicals have been major soil and groundwater contaminants especially in the nations with active military activities. Of these explosives, 2,4,6-trinitrotoluene (TNT) is the most refractory one due to its structural characteristics. Although its efficient reduction by Fe(0) is well-known, the reduction products - mainly aminotoluenes - still possess toxicities to terrestrial biota, and are resistant to biological degradation. In this study, therefore, abiotic transformation of TNT reduction products via oxidative-coupling reaction was evaluated using Mn oxide which is ubiquitous in natural soils. The transformation efficiency is increased with the number of amino groups. Considering the very efficient reduction rate of TNT by Fe(0), Mn oxide can be successfully used for the removal of TNT reduction products.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.49-52
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• 2005

In this study, abiotic transformation of 1-naphthol via oxidative-coupling reaction was evaluated using Mn oxide which is ubiquitous in natural soils. The transformation of 1-naphthol catalyzed by synthetic birnessite $({\delta}-MnO_2)$ followed pseudo-lst order reaction, and the rate constants was in the range of $0.053{\sim}0.13\;min^{-1}$ with birnessite loadings of $12.5{\sim}50\;mg/20\;mL$. Since the oxidation of 1-naphthol was occurred on the reactive surface of the oxide particles, the rate constants with various birnessite loadings were correlated with birnessite surface area concentration. The correlation showed a strong linearity, which confirms the supposition of the surface reaction. From the correlation, therefore, the surface area normalized rate constant, $k_{surf}$, was determined to be 0.032 $L/m^2\;min$.

• Korean Journal of Plant Tissue Culture
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• v.28 no.2
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• pp.87-90
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• 2001

BcGRl gene encoding cytosolic glutathione reductase of Chinese cabbage (Brassica campestris var. Pekinensis cv. Seoul) was placed under the control of the CaMV 35S promoter and introduced into tobacco (Nicotiana tabacum L. cv. Samsun) via Agrobacterium-mediated transformation. T$_{0}$ 32 independent plants transformed with BcGRl gene were selected with kanamycin and they were confirmed by polymerase chain reaction (PCR) and Southern blot analysis. Northern blot analysis revealed that the constitutive expression of BcGRl gene and there was no relationship between the copy number of introduced gene and the levels of BcGRl transcripts.