• The Korean Journal of Pharmacology
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• 제29권2호
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• pp.275-282
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• 1993

Liver microsomal epoxide hydrolase (mEH) is active in the detoxification of epoxide-containing reactive intermediate. Previous studies in this laboratory have shown that thiazole and pyrazine are efficacious inducers of mEH in rats with large increases in mEH mRNA levels (Carcinogensis, Kim et al, 1993). mEH was purified to electrophoretic homogeneity from thiazole-induced rat hepatic microsomes using DEAE-cellulose column chromatography whereas another protein $({\sim}43\;kDa)$ was co-purified with mEH from pyrazine-induced rat hepatic micrsomes (200 mg/kg body weight/day, ip, 3d). The antibody raised from a rabbit against mEH protein purified from thiazole-induced rat hepatic microsomes appeared to specifically recognize mEH protein in rat hepatic microsomes, as assessed by immunoblotting analysis. Immunoblotting analyses revealed a 10- and 7-fold increase in mEH levels in the hepatic microsomes isolated from thiazole- and pyrazine-treated rats, respectively. Moreover, immunoblotting analysis showed cross-reactivity of the mEH antibody with a 43 kDa protein in pyrazine-induced rat hepatic microsomes and with co-purified 43 kDa protein in purified fractions. The ratio between the 43 kDa protein and mEH in pyrazine-induced rat microsomes or in purified fractions was ${\sim}1$ to 15. N-terminal amino acid sequence analysis of both purified rat mEH and 43 kDa protein revealed that 10 out of 12 amino acids in N-terminus of the 43 kDa protein were identical with the mEH sequence with two amino acid residues of the 43 kDa protein undetermined. Either thiazole or pyrazine treatment, however, failed to increase the levels of mEH protein in rabbits while pyrazine caused elevation of the 43 kDa protein in this species, as determined by irnrnunoblotting analysis. These results demonstrated that treatment of rats with either thiazole or pyrazine causes elevation in hepatic mEH expiession whereas pyrazine treatment results in induction of another mEH-related 43 kDa protein and that a distinct species difference exists between rats and rabbits in the induction of mEH by these xenobiotics.

• Microbiology and Biotechnology Letters
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• 제34권2호
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• pp.129-135
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• 2006

A gene encoding for a putative microsomal epoxide hydrolase (mEH) of a zebrafish, Danio rerio, was cloned and characterized. The putative mEH protein of D. rerio exhibited sequence similarity with mammalian mEH and some other bacterial EHs. A structural model for the putative mEH was constructed using homology modeling based on the crystallographic templates, 1 qo7 and 1 ehy. The catalytic triad consisting of $Asp^{233}$, $Glu^{413}$, and $His^{440}$ was identified, and the characteristic features such as two tyrosine residues and oxyanion hole were found to be highly conserved. Based on bioinformatic analysis together with EH activity assay, the putative protein was annotated as mEH of D. rerio. Enantiopure styrene oxide with enantiopurity of 99%ee and yield of 33.5% was obtained from racemic styrene oxide by the enantioselective hydrolysis activity of recombinant mEH of D. rerio for 45 min.

• YAKHAK HOEJI
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• 제51권5호
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• pp.291-295
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• 2007

The present study examines the effect of dominant-negative Akt on the insulin-mediated microsomal epoxide hydrolase (mEH) induction in rat hepatocytes. We also assessed the role of insulin in the expression of soluble epoxide hydrrolase (sEH). Insulin increased mEH levels and the enzyme activities, whereas sEH protein expression was unaffected by insulin. The specific PI3K inhibitors or p70 S6 kinase inhibitor ameliorated the insulin-mediated increase in mEH protein levels. Infection with adenovirus expressing dominant-negative and kinase-dead mutant of Akt1 effectively inhibited the insulin-mediated increase in mEH expression and mEH activity. These results suggest that mEH and sEH are differentially regulated by insulin and PI3K/Akt/p70S6K are active in the insulin-mediated regulation of mEH expression.

• Asian Pacific Journal of Cancer Prevention
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• 제13권2호
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• pp.521-525
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• 2012

Microsomal epoxide hydrolase (mEH) plays a significant role in the metabolism of numerous xenobiotics and is associated with several forms of cancer. Here, we investigated the role of mEH expression in bladder carcinogenesis, subsequent progression and recurrence. The expression of mEH was analyzed by Western blot in 50 bladder urothelial carcinoma and 20 normal epithelial tissues. There was a significantly higher mEH expression in the normal epithelium (P<0.05) and mEH expression was lower in high stage than in low stage tumors (P<0.05). Further, immunohistochmistry in 106 bladder urothelial carcinoma demonstrated mEH expression to be negatively correlated with histological grade, pT stage and recurrence (P<0.05). These findings suggest the important role of mEH in bladder carcinogenesis, cancer development and recurrence, providing support for efforts to develop mEH-based gene therapy.

• The Korean Journal of Pharmacology
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• 제32권2호
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• pp.233-241
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• 1996

Previous studies have shown that glucocorticoid suppresses microsomal epoxide hydrolase(EH) gene expression and that EH expression is altered during pregnancy. The effects of progesterone on the expression of rat EH and certain glutathione S-transferase(GST) genes were examined in this study. Northern RNA blot analysis revealed that progesterone was effective in increasing hepatic EH mRNA levels at 12 h to 48 h after treatment with a maximal 9-fold increase being noted at 12 h time point. Nonetheless, multiple daily treatment with progesterone rather caused minimal relative increases in EH mRNA levels. GST Ya and Yb1/2 mRNA levels were also transiently elevated at 12 h after progesterone treatment, followed by gradual decreases from the maximal Increases at day 1, 2 and 5 post-treatment. These changes in EH and GST mRNA levels were noted only at a relatively high dose of progesterone. Furthermore, immunoblot analyses showed that rats treated with progesterone for 5 days failed to show EH or GST induction, indicating that progesterone-induced alterations in EH and GST mRNA levels do not reflect bona fide induction of the detoxifying enzymes. Concomitant progesterone treatment of rats with the known EH inducers including ketoconazole and clotrimazole failed to additively nor antagonistically alter EH mRNA levels. In contrast, dexamethasone substantially reduced ketoconazole- or clotrimazole-inducible EH expression. These results showed that progesterone stimulates the EH, GST Ya and Yb1/2 gene expression at early times followed by marked reduction in the RNA levels from the maximum after multiple treatment and that the changes in mRNA do not necessarily reflect induction of the proteins.

• Microbiology and Biotechnology Letters
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• 제35권4호
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• pp.285-291
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• 2007

Enantioconvergent hydrolysis process for the preparation of chiral diol from racemic epoxides by using the recombinant Caulobacter crescentus epoxide hydrolase (CcEH) in Escherichia coli BL21 (DE3) was optimized. For the optimization, the effects of detergent, temperature and product inhibition on the enantiopurity and the yield of diol were investigated. (R)-phenyl-1,2-ethanediol with 92% enantiomeric excess and 56% yield from 20 mM racemic styrene oxide was obtained by using the recombinant CcEH at the optimal condition of $10^{\circ}C$ and the addition of 2% (w/v) Tween 80. At 50 mM racemic styrene oxide was used as a substrate, (R)-phenyl-1,2-ethanediol was obtained with 87% enantiomeric excess and 77% yield. Racemic phenyl-1,2-ethanediol, (R)-phenyl-1,2-ethanediol and (S)-phenyl-1,2-ethanediol dramatically inhibited the hydrolytic activity of the recombinant CcEH. These results suggested that another EH with the regioselectivity on ${\beta}$-position of (R)-enantiomer and without feedback inhibition by products would be needed as the partner EH of C. crescentus EH.

• Journal of Korean Society of Environmental Engineers
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• 제28권2호
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• pp.144-149
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• 2006

As a strain EH741, having an excellent hexane degradability, was isolated from bacterial consortium using hexane as a sole carbon and energy source. EH741 was identified as a Rhodococcus sp. and the addition of a surfactant Pluronic F68(PF68), for increasing hexane solubility couldn't enhance the specific growth rate of the isolate EH741 n the mineral salt medium supplemented with hexane as a sole carbon source(hexane-BH medium). In the hexane-BH medium, the maximum specific growth rate(${\mu}_{max}$) of this strain was $0.04h^{-1}$, and the maximum hexane degradation rate($V_{max}$) and saturation constant($K_s$) were$161{\mu}mol{\cdot}g-DCW^{-1}{\cdot}h^{-1}$ and 10.5 mM, respectively. Rhodococcus sp. EH741 was one of excellent microorgamisms for hexane biodegradation processes.

• Toxicological Research
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• 제13권4호
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• pp.339-347
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• 1997

Disulfiram (DSF) and diethyldithiocarbamate (DDC), a reduced form of DSF, protect the liver against toxicant-induced injury through inhibition of cytochrome P450 2E1. The effect of DSF and DDC on the levels of major hepatic microsomal epoxide hydrolase (mEH) and glutathione S-transferase (GST) expression was comparatively studied, given the view that these enzymes are involved in terminal detoxification events for high energy intermediates of xenobiotics. Treatment of rats with a single dose of DSF (20-200 mg/kg, po) resulted in 2- to 15-fold increases in the mEH mRNA level at 24 hr with the ED$_{50}$ value being noted as 60 mg/kg. The mEH mRNA level was elevated ~15-fold at 24 hr after treatment at the dose of 100 mg/kg, whereas the hepatic mRNA level was rather decreased from the maximum at the dose of 200 mg/kg, indicating that DSF might cause cytotoxicity at the dose. In contrast to the effect of DSF, DDC only minimally elevated the mEH mRNA level at the doses employed. DSF moderately increased the major GST mRNA levels in the liver as a function of dose, resulting in rGSTA2, rGSTA3/5 or rGSTM1 mRNA levels being elevated 3- to 4-fold at 24 hr post-treatment, whereas the rGSTM2 mRNA level was not altered. DDC, however, failed to stimulate the mRNA levels for major GST subunits, indicating that the reduced form of DSF was ineffective in stimulating the GST the expression. The effect of other organosulfides including aldrithiol, 2, 2'-dithiobis(benzothiazole) (DTB), tetramethylthiouram disulfide (TMTD) and allyl disulfide (ADS) on the hepatic mEH and GST mRNA expression was assessed in rats in order to further confirm the increase in the gene expression by other disulfides. Treatment of rats with aldrithiol (100 mg/kg, po) resulted in a 16-fold increase in the mEH mRNA level at 24 hr post-treatment. DTB, TMTD and ADS also caused 5-, 9- and 12-fold increases in the rnRNA level, respectively, as compared to control. Thus, all of the disulfides examined were active in stimulating the mEH gene in the liver. The organosulfides significantly increased the rGSTA2, rGSTA3, rGSTA5 and rGSTM1 mRNA levels at 24 hr after administration. In particular, aldrithiol was very efficient in stimulating the rGSTA and rGSTM genes among the disulfides examined. These results provide evidence that DSF and other sulfides effectively stimulate the mEH and major GST gene expression at early times in the liver and that DDC, a reduced form of DSF, was ineffective in stimulating the expression of the genes, supporting the conclusion that reduced form(s) of organosulfur compound(s) might be less effective in inducing the mEH and GST genes through the antioxidant responsive element(s).

• Journal of Life Science
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• 제12권5호
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• pp.570-576
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• 2002

The extremely halophilic archaebacterium Haloarcular sp. EH-1 was isolated from solar salts. Amylae production from Halonrcular sp. EH-1 have been studied. The results obtained were as follows. The optimal medium composition for the production of amylase from Haloarcular sp. EH-1 were soluble starch 1.5%, yeast extract 1.0%, MgSO$_4$ 7h$_2$O 2.0%, KCI 0.1%, NaCl 25% (pH 7.5). The incubation temperature, aeration rate and agitation speed were 4$0^{\circ}C$, 100 $m\ell$ medium / 500 $m\ell$ shaking flask, and 110 rpm. The cell growth and enzymatic activity was highest at 9 days of incubation. So amylase production appeared to be a growth-related phenomenon.

• Applied Chemistry for Engineering
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• 제18권3호
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• pp.279-283
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• 2007

Epoxide hydrolase (EH) gene of Caulobacter crescentus was cloned by PCR and expressed in Escherichia coli. The C. crescentus EH (CcEH) primarily attacked at the benzylic carbon of (S)-styrene oxide, while the CcEH preferentially attacked at the terminal carbon of (R)-styrene oxide, thus leading to the formation of (R)-phenyl-1,2-ethanediol as the main product. (R)-phenyl-1,2-ethanediol was obtained with 85% enantiomeric excess and yield of 69% from racemic styrene oxide via enantioconvergent hydrolysis by using recombinant CcEH as the single biocatalyst.