• Proceedings of the Korean Society of Applied Pharmacology
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• 1998.11a
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• pp.108-113
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• 1998

Egasyn is accessory protein of ${\beta}$-glucuronidase(${\beta}$-G) in the liver microsomes. Liver microsomal ${\beta}$-G is stabilized within the luminal site of the microsomal vesicles by complexation with egasyn which is one of carboxylesterase isozymes. We investigated the effects of organophosphorus compounds(OPs) such as insecticides on the dissociation of egasyn-${\beta}$-glucuronidase(EG) complex. The EG complex was easily dissociated by administration of OPs, i.e., Fenitrothion, EPN, Phenthionate, and bis-p-nitrophenyl phosphate(BNPP), and resulting ${\beta}$-G dissociated was released into blood, leading to the rapid and transient increase of plasma ${\beta}$-G level with a concomitant decrease of liver microsomal ${\beta}$-G level. In a case of phenthionate treatment, less increase in plasma ${\beta}$-G level was observed, as compared with those of other OPs. This may be explained by a fact that phenthionate was easily hydrolyzed by carboxylesterase. Similarly, carbamate insecticides such as Carbaryl caused rapid increase of plasma ${\beta}$-G level. In contrast, no significant increase of plasma ${\beta}$-G level was observed when pyrethroid insecticides were administered to rats. This is due to a fact that pyrethroids such as Phenthrin and Allethrin were easily hydrolyzed by A-esterase as well as carboxylesterase. On the other hand, addition of OPs to the incubation mixture containing liver microsomes caused the release of ${\beta}$-G from microsomes to the medium. From these in vivo and in vitro data, it is concluded that increase of the plasma ${\beta}$-G level after OPs administration is much more sensitive biomarker than cholinesterase inhibition to acute intoxication of OPs and carbamates.

• BMB Reports
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• v.49 no.6
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• pp.349-354
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• 2016

The archaeon Sulfolobus solfataricus P1 carboxylesterase is a thermostable enzyme with a molecular mass of 33.5 kDa belonging to the mammalian hormone-sensitive lipase (HSL) family. In our previous study, we purified the enzyme and suggested the expected amino acids related to its catalysis by chemical modification and a sequence homology search. For further validating these amino acids in this study, we modified them using site-directed mutagenesis and examined the activity of the mutant enzymes using spectrophotometric analysis and then estimated by homology modeling and fluorescence analysis. As a result, it was identified that Ser151, Asp244, and His274 consist of a catalytic triad, and Gly80, Gly81, and Ala152 compose an oxyanion hole of the enzyme. In addition, it was also determined that the cysteine residues are located near the active site or at the positions inducing any conformational changes of the enzyme by their replacement with serine residues.

• Journal of Life Science
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• v.20 no.9
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• pp.1306-1313
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• 2010

The gene encoding esterase enzyme was cloned from a metagenomic library of cow rumen bacteria. The esterase gene (est1R) was 2,465 bp in length, encoding a protein of 366 amino acid residues, and the molecular weight of the enzyme was 61,166 Da. Est1R of rumen cosmid library shared 5.9% amino acid identity with Est1R (P37967) of PNB carboxylesterase, 6.1% with Est1R (1EEAA) of acetylcholinesterase and 6.1% with Est1R (1H23A) of chain A. BlastP in NCBI database analysis of Est1R revealed that it was not homologous to previous known lipases and esterases. Est1R showed optimum activity at pH 7.0 and $40^{\circ}C$. On the other hand, the enzyme was found to be most active without organic solvent, followed by 95% activity with methanol, and the enzyme activity was highly affected by hexane (lost 51% activity). Therefore, the novel esterase gene est1R is likely obtainable from cow rumen metagenome and may be utilized for industrial purposes.

• Proceedings of the Korean Society of Tobacco Science Conference
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• 1998.05a
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• pp.29-29
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• 1998

• Environmental Analysis Health and Toxicology
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• v.7 no.3_4
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• pp.57-67
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• 1992

BPMC (2-Sec-butylphenyl N-methylcarbamate) was treated at the level of 100mg/kg/day in oral administration for 12th days in rat. It was investigated not only that the hematogram and the serological parameters, but also the content of cytochrome P-450, the activity of TBA, glucose-6-phosphatase, cholinesterase and carboxylesterase in rat. The results were as follows: The hematogram was not found any alteration but the value of AST, ALT, LDH and the content of glucose in serum were significantly increased compare with that of control group. The content of cytochrome P-450 in liver was increased significantly on the contrary cytochrome P-450 in kideny and NADPH-cytochrome c reductase in liver and Kidney were not significantly increased. After the final 12th day, the value of TBA and the activity of glucose-6-phosphatase appeared to the tendency of increasement in the liver. The activity of cholinesterase and carboxylesterase both in serum and liver were decreased. Especially the activity of cholinesterase was more significantly decreased. It was conclusion that the function of this insectivide should be due th the inhibition of cholinesterase activity.

• Environmental Analysis Health and Toxicology
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• v.8 no.1_2
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• pp.1-10
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• 1993

This study was done to determine the toxic effect of fthalide in rats which have oral administration at levels of 100 mg/kg/day for twelve days. It was examined the hematogram and serological parameters, and also the content of cytochrome P-450, the activity of NADPH-cytochrome c reductase, glucose-6-phosphatase, cholinesterase and carboxylesterase in liver. Any significant alteration of hematogram was not found but the value of AST, LDH and content of glucose in serum were statistically increased. The content of cytochrome P-450, the activty of NADPH-cytochrome c reductase were increased but glucose-6-phosphatase were slightly decreased compare with that of control group. The activity of cholinesterase was decreased slightly and on the contrary the activity of carboxylesterase was found to be the tendeny of increase in both of liver and serum.

• Proceedings of the Zoological Society Korea Conference
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• 1998.10b
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• pp.250.2-250
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• 1998

No Abstract, See Full Text

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.188.2-188
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• 1999

No Abstract, See Full Text

• Journal of the Korean Society of Tobacco Science
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• v.21 no.2
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• pp.160-170
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• 1999

Purification and biochemical experiments on the carboxylesterases-III (CE-III) from the indian meal moth, Plodia interpunctella (Hubner) were carried out to understand their enzymemological characteristics. The CE-III from the fifth instar larvae was purified by means of ammonium sulfate fractionation, gel permeation choromatography and ion exchange choromatography. The optimal temperature for the reaction of the CE-III on the 4 substrates ($\alpha$-Na, $\alpha$-Nb, $\beta$-Na and $\beta$-Nb) was confirmed at 4$0^{\circ}C$. The optimal pH for the reactions on the substrates $\alpha$-Na and $\alpha$-Nb was 7.5. But the optimal pH on the substrate $\beta$-Na and $\beta$-Nb was 8.0. The optimal substrate concentration for the reactions of the CE-III was 3.16 X 10$^{-3}$ M in $\alpha$-Na and $\beta$-Nb. On the substrate $\beta$-Na and $\alpha$-Nb, the optimal substrate concentration was 1.0 X 10$^{-3}$ M for CE-III. The $V_{max}$ and $K_{m}$ values of the carboxylesterases were varied by the substrates as followings: the $V_{max}$ of CE-III was 45.9 for $\alpha$-Na, 52.6 for $\beta$-Na, 36.4 for $\alpha$-Nb, and 83.3 ($\mu$ mol/min/mg protein) for $\beta$-Nb. The $K_{m}$ of CE-III was 1.43 X 10$^{-4}$ M for $\alpha$-Na, 3.57 x 10$^{-5}$ M for $\beta$-Na, 9.17 X 10$^{-5}$ M for $\alpha$-Nb, and 7.14 X 10$^{-5}$ M for $\beta$ -Nb, respectively. The CE-III seemed to have somewhat high thermostability considering that the temperature for effective denaturation on activity was about 5$0^{\circ}C$ ～ 6$0^{\circ}C$.EX>.EX>.

• Applied Biological Chemistry
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• v.35 no.5
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• pp.367-374
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• 1992

This study was performed to investigate effects of probable detoxifying enzyme activity and toxicity by pesticides and their combinations in the fresh water fish. Seven pesticides including IBP, isoprothiolane, cartap, ridomil, chlorothalonil, captafol and endosulfan were subjected to investigate for their acute toxicites and synergism possibilities. The $LC_{50}$ value of endosulfan was the lowest at showing 0.0079 ppm and that of metalaxyl was the highest as showing 40 ppm over. The synergism effects of relative pesticides were observed in the combinations of isoprothiolane+IBP and isoprothiolane+cartap. The changes of glycogen contents in fish liver were assayed for 5 pesticides and its highest inhibition effect of glycogen showed in IBP treated fish. The activity of probable detoxifying enzymes including carboxylesterase (CE), glutathion S-transferase (GST) and lactate dehydrogenase (LDH) were assayed in carp liver at dose of sublethal concentrations. Effects of pesticides on changes in each enzyme activities were as follows: carboxylesterase (CE) activities were the highest in IBP and gtutathion S-transferase (GST) activities were the highest in iosoprothiolane+IBP. Both activities of carboxylesterase (CE) and glutahtion S-transferase (GST) were increased by 5 chemicals. The highest LDH activity showed in isoprothiolane treated fish, while the lowest activity was observed in isoprothiolane+cartap. Sublethal exposure to cartap and isoprothiolane+cartap in carp exerted various effects on LDH activity.