• Journal of Microbiology and Biotechnology
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• 제28권9호
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• pp.1502-1510
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• 2018

Organic solvent-tolerant (OST) enzymes are widely applied in various industries for their activity and stability in organic solvents, for their higher substrate solubility, and for their greater stero-selectivity. However, the criteria for identifying OST enzymes largely remain undefined. In this study, we compared the amino acid composition of 19 OST esterases with that of 19 non OST esterases. OST esterases have increased the ratio of Ala and Arg residues and decreased the ratio of Asn, Ile, Tyr, Lys, and Phe residues. Based on our amino acid composition analysis, we cloned a carboxylesterase (EstSP2) from a psychrophilic bacterium, Sphingomonas glacialis PAMC 26605, and characterized its recombinant protein. EstSP2 is a substrate specific to p-nitrophenyl acetate and hydrolyzed aspirin, with optimal activity at $40^{\circ}C$; at $4^{\circ}C$, the activity is approximately 50% of its maximum. As expected, EstSP2 showed tolerance in up to 40% concentration of polar organic solvents, including dimethyl sulfoxide, methanol, and ethanol. The results of this study suggest that selecting OST esterases based on their amino acid composition could be a novel approach to identifying OST esterases produced from bacterial genomes.

• International Journal of Industrial Entomology and Biomaterials
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• 제9권1호
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• pp.59-63
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• 2004

By using PAGE, a study was made on the nonspecific esterase spectra of female genital organs and eggs in Bombyx mori L. The expression of 11 esterase bands was detected during ontogenesis of races and inter-races hybrids kept in Bulgaria. The gene activity of 9 esterase loci was assumed. Esterases specific for the spectrum of diapausing eggs were observed. In two esterase zones, intra- and inter-breed polymorphism was found. Based on the same breed specific expression, the existence of correspondence between esterase bands from spectra of different silkworm tissues and organs was suggested. Stage-specific expression of esterases in female genital glands, indicative of differentiated gene activity during ontogenesis, was established.

• Journal of Microbiology and Biotechnology
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• 제5권5호
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• pp.274-279
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• 1995

Ethyl caproate, one of the major flavor compounds deciding the quality of sake (Japanese wine), is produced during the brewing by the action of alcohol acyltransferase and esterases of sake yeast and koji mold. Extracellular esterases of Aspergillus oryzae required for ethyl caproate synthesis were purified partially. The enzymes had different optimum pH and affinity toward substrates. Substrate preferences and inhibition features showed the three enzymes to be B-type esterases or carboxylesterases (EC 3.1.1.1).

• 한국미생물·생명공학회지
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• 제26권1호
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• pp.50-54
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• 1998

청주가 가지고 있는 향기는 청주의 품질을 결정하는 요인 중의 하나이다. 청주의 향기는 발효과정 중 주로 효모에 의해서 발생하는 것으로 알려지고 있고, ethyl caproate는 향기성분 중의 하나로 esterase가 생성에 관여하고 있는 효소의 하나로 보고되었다. 반면 청주 제조에 사용되는 청주효모와 코지균은 ethyl caproate의 생성과 분해 활성을 가진 esterase를 생산하는 것으로 보고되었다. 본 연구에서는 청주 제조 중 발생하는 ethyl Caproate의 생성에 미치는 청주효모와 코지균이 가지고 있는 esterase들의 영향을 알아보기 위하여 코지균과 청주효모의 생장 중 발생하는 ethyl caproate 합성과 분해에 관련하고 있는 esterase들의 활성 변화에 대하여 알아보았다. 청주효모가 가지고 있는 ethyl caproate 합성 esterase는 caproate에 의해서 유포되고, 분해 esterase는 ethyl caproate에 의해서 유도되지만 caproate에 의해서 저해되는 것으로 나타났다. 코지균의 ethyl caproate합성과 분해 esterase활성은 균체의 성장에 비례하여 증가하였으나 ethyl caproate 생성의 기질이 되는 caproate와 ethanol이 활성에 영향을 미치지 못하는 것으로 나타났다. 또한 코지균의 배양액에서 ethyl caproate 합성 esterase의 활성이 측정됨에도 불구하고 0.01 ppm까지 ethyl caproate를 검출할 수 있는 분석조건 하에서 배지 중의 ethyl caproate는 검출되지 않았다. 본 실험의 결과를 고려한다면 청주의 제조과정 중 생성되는 ethyl caproate는 코지균의 esterase에 의해서는 거의 생성되지 않고 당화과정 후 첨가되는 청주효모가 주로 생성하는 것으로 확인되었다. 또한 청주효모의 증식과정 중에는 효모의 생장과 더불어 ethanol이 생성되어 코지균의 생장을 억제한다. 따라서 청주제조 중 생성되는 ethyl caproate는 청주효모의 esterase에 의해 생산된 것으로 사료된다.

• 한국연초학회지
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• 제21권1호
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• pp.49-56
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• 1999

Classification of esterase isozymes of the apterous green peach aphids (Myzus persicae Sulzer) collected in tobacco fields were investigated by the native polyacrylamide gel electrophoresis (PAGE). A total of twelve esterase bands were identified in adult apterous aphid, and the difference of enzyme band activity in the clones was observed at the first and second bands group. Esterases of green peach aphids reacted with specific substrate were more stained $\alpha$-naphthyl acetate than $\alpha$-naphthyl propionate, and $\alpha$-naphthyl acetate more than $\beta$-naphthyl acetate. Twelve esterases on the basis of inhibition by the three types of inhibitors (organophosphates: 2.5$\times$10$^{-3}$ M paraoxon, 4$\times$10$^{-3}$ M DFP; eserine sulfate : 2$\times$10$^{-3}$ M eserin; sulfhydryl reagents: 2$\times$10$^{-3}$ M p-HMB) were classified into three class, namely, cholinesterase (ChE) I, II, carboxylesterase (CE) and arylesterase (ArE), and these classes contained 3, 4, 3 and 2 isozymes, respectively.

• Toxicological Research
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• 제22권1호
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• pp.1-8
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• 2006

The primary metabolism of pyribenzoxim was studied in rat liver microsomes in order to identify the cytochrome P450 (CYP) isoform(s) and esterases involved in the metabolism of pyribenzoxim. Chemical inhibition using CYP isoform-selective inhibitors such as ${\alpha}$-naphthoflavone, tolbutamide, quinine, chlorzoxazone, troleandomycin, and undecynoic acid indicated that CYP1A and CYP2D are responsible for the oxidative metabolism of pyribenzoxim. And inhibitory studies using eserine, bis-nitrophenol phosphate, dibucaine, and mercuric chloride indicated pyribenzoxim hydrolysis involved in microsomal carboxylesterases containing an SH group (cysteine) at the active center.

• Journal of Microbiology and Biotechnology
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• 제21권12호
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• pp.1203-1210
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• 2011

Function-driven metagenomic analysis is a powerful approach to screening for novel biocatalysts. In this study, we investigated lipolytic enzymes selected from an alluvial soil metagenomic library, and identified two novel esterases, EstDL26 and EstDL136. EstDL26 and EstDL136 reactivated chloramphenicol from its acetyl derivates by counteracting the chloramphenicol acetyltransferase (CAT) activity in Escherichia coli. These two enzymes showed only 27% identity in amino acid sequence to each other; however both preferentially hydrolyzed short-chain p-nitrophenyl esters (${\leq}C_5$) and showed mesophilic properties. In vitro, EstDL136 catalyzed the deacetylation of 1- and 3-acetyl and 1,3-diacetyl derivates; in contrast, EstDL26 was not capable of the deacetylation at $C_1$, indicating a potential regioselectivity. EstDL26 and EstDL136 were similar to microbial hormone-sensitive lipase (HSL), and since chloramphenicol acetate esterase (CAE) activity was detected from two other soil esterases in the HSL family, this suggests a distribution of CAE among the soil microorganisms. The isolation and characterization of EstDL26 and EstDL136 in this study may be helpful in understanding the diversity of CAE enzymes and their potential role in releasing active chloramphenicol in the producing bacteria.

• 농약과학회지
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• 제7권1호
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• pp.38-44
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• 2003

본 연구는 다양한 계열의 농약을 대상으로 체내에서 농약을 무독화하는 효소로 알려진 glutathione-S-transferase(GST) 와 esterases 에 대한 저해정도를 조사하고, 이 중 저해력이 높은 약제를 선발하여 무독화 효소에 의하여 분해되는 것으로 보고된 약제와 혼합 처리하였을 때 나타나는 약효의 변화를 조사하고자 수행하였다. 무독화효소를 저해하는 농약을 선발하기 위하여 34종의 살충제와 31종의 살균제를 대상으로 glutathione-S-transferase와 esterases 에 대한 저해력을 측정한 결과, thiodicarb $(I_{50}:1.87{\times}10^{-4}M)$, thiocyclarn $(I_{50}:7.40{\times}10^{-4}M)$, dithianon $(I_{50}:7.55{\times}10^{-5}M)$, tolylfluanide $(I_{50}:8.66{\times}10^{-5}M)$은 glutathione-S-transferase의 활성을 강게 저해하였고, dichlorvos $(I_{50}:8.95{\times}10^{-8}M)$, pirimicarb $(I_{50}:2.74{\times}10^{-6}M)$, pyrazophos $(I_{50}:3.31{\times}10^{-5}M)$, benomyl $(I_{50}:4.96{\times}10^{-5}M)$은 esterases의 활성을 강하게 저해하였다. Glutathione-S-transferase를 저해하였던 thiodicarb, thiocyclarn, dithianon, tolylfluanide와 glutathione-S-transferase 에 의해 대사되는 것으로 알려진 aeephate를 혼합 (1:1)하여 배추좀나방 (Plutella xylostella L.) 에 처리하고 약효를 관찰한 결과, 각각의 단제를 처리하였을 때보다 약효가 상승되었다. 특히 dithianon과 thiocyclam을 acephate 와 혼합시 각각 7배와 4배 약효가 상승하였다. 그리고 esterase를 저해한 약제인 dichlorvos, pirimicarb, pyrazophos, benomyl 을 esterase 에 의해 대사되는 것으로 알려진 phenthoate 와 혼합하였을 경우에도 단제 처리시의 약효보다는 혼합처리시의 약효가 높았다. Phenthoate와 dichlorvos 혼합시 18배, phenthoate 와 benomyl 혼합처리시 12배의 약효상승효과가 나타났다. 본 연구의 결과들은 무독화과정 효소에 의해 무독화되는 약제를 무독화효소 저해제와 혼합처리시 약효상승이 유발된다는 것을 나타내는데, 이러한 결과들은 향후 혼합제 개발에 유용하게 사용될 수 있을 것이라 생각된다.

• 농약과학회지
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• 제10권1호
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• pp.50-55
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• 2006

본 연구는 강원도 고랭지 배추경작지에서 채집한 chlorpyrifos 포장저항성 계통의 배추좀나방에서 추출한 무독화 효소 esterases와 glutathione-S-tranferase(GST)의 활성과 단백질의 sequestration 비율 및 acetylcholinesterase(AChE) insensitivity를 측정하여 저항성 발달기작을 구명하고자 수행되었다. Esterases의 경우 저항성과 감수성 배추좀나방간의 활성 차이는 없었으나, 전기영동상에서는 특정 isozyme의 차이가 확인되었으며, GST 활성은 포장저항성 계통이 감수성 계통보다 약 1.5배 높았다. 두 계통 간 단백질의 sequestration 차이는 없었으며, chlorpyrifos에 대한 AChE의 sensitivity는 포장저항성 계통의 AChE가 감수성계통보다 약 460배 낮은 것으로 확인되었다. 이러한 결과는 실내에서 저항성을 유도하여 파악한 배추좀나방의 저항성 특성결과와 동일한 것으로 강원도 고랭지 chlorpyrifos 포장저항성 배추좀나방의 저항성 발달은 AChE의 insensitivity가 주요 요인이며, 부가적으로 GST의 활성 변화도 작용하는 것으로 판단되었다.

• Journal of Applied Biological Chemistry
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• 제44권3호
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• pp.105-112
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• 2001

Insect pests can be controlled through direct application of insecticides. Insect control by residual protectants is relatively inexpensive and has an advantage of destroying all stages of infestations. The efficacy of control is largely determined by the concentration of insecticides to which the pest species is exposed. A reduction in the period of control in the field afforded by a specific level of a protectant indicates that resistance has developed. An increase in the level of protectant is required to maintain control, and the efficacy of currently used insecticides has been severely reduced by insecticide resistance in pest species. Development of resistance to particular insecticide varies with species because insecticide resistance is often correlated with increased levels of certain enzymes, which are cytochrome P450-dependent monooxygenases, glutathione S-transferases and esterases. Some sections of insecticide molecules can be modified by one or more of these primary enzymes. A reduction in the sensitivity of the action site of a xenobiotic also constitutes a mechanism of resistance. Acetylcholinesterase is a major target site for insecticide action, as are axonal sodium ion channels and ${\gamma}$-aminobutyric acid receptors. Development of reduced sensitivity of these target sites to insecticides usually occurs. This review not only may contribute to a better understanding of insecticide resistance, but also illustrates the gaps still present for a full biochemical understanding of the resistance.