• KSBB Journal
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• v.23 no.5
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• pp.369-374
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• 2008

The effects of reaction temperature and the addition of various detergents on the enantioselective hyrolysis activity of the recombinant Escherichia coli containing the epoxide hydrolase (EH) gene of Rhodotorula glutinis were investigated for the production of enantiopure styrene oxide. The recombinant E. coli harboring the EH gene from R. glutinis exhibited the enantiopreference toward (R)-styrene oxide with the maximum hydrolytic activity of $165.04{\mu}mol/min/mg$ of dry cell weight (dcw). The addition of 0.5% (w/v) Tween 20 at $10^{\circ}C$ increased the initial hydrolysis rate and enantioselectivity by 1.45-fold and 2.0-fold, respectively. Enantiopure (S)-styrene oxide was prepared with 99% ee enantiopurity and 46.0% yield (theoretical yield=50%) from 20 mM racemic styrene oxide.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.529-536
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• 2003

The growth-inhibitory activity of Cassia tora seed-derived materials against seven intestinal bacteria was examined in vitro, and compared with that of anthraquinone, anthraflavine, anthrarufin, and 1-hydroxyanthraquinone. The active constituent of C. tore seeds was characterized as quinizarin, using various spectroscopic analyses. The growth responses varied depending on the compound, dose, and bacterial strain tested. At 1 mg/disk, quinizarin exhibited a strong inhibition of Clostridium perfringens and moderate inhibition of Staphylococcus aureus without any adverse effects on the growth of Bifidobacterium adolescentis, B. bifidum, B. longum, and Lactobacillus casei. Furthermore, the isolate at 0.1 mg/disk showed moderate and no activity against C. perfringens and S. aureus. The structure-activity relationship revealed that anthrarufin, anthraflavine, and quinizarin moderately inhibited the growth of S. aureus. However. anthraquinone and 1-hydroxyanthraquinone did not inhibit the human intestinal bacteria tested. As for the morphological effect of 1 mg/disk quinizarin, most strains of C. perfringens were damaged and disappeared, indicating that the strong activity of quinizarin was morphologically exhibited against C. perfringens. The inhibitory effect on aflatoxin $B_1$ biotransformation by anthraquinones revealed that anthrarufin ($IC_50,\;11.49\mu\textrm{M}$) anthraflavine ($IC_50,\;26.94\mu\textrm{M}$), and quinizarin ($IC_50,\;4.12\mu\textrm{M}$), were potent inhibitors of aflatoxin ${B_1}-8,9-epoxide$ formation. However, anthraquinone and 1-hydroxyanthraquinone did not inhibit the mouse liver microsomal sample to convert aflatoxin $B_1$ to aflatoxin ${B_1}-8,9-epoxide$. These results indicate that the two hydroxyl groups on A ring of anthraquinones may be essential for inhibiting the formation of aflatoxin ${B_1}-8,9-epoxide$. Accordingly, as naturally occurring inhibitory agents, the C. tora seed-derived materials described could be useful as a preventive agent against diseases caused by harmful intestinal bacteria, such as clostridia, and as an inhibitory agent for the mouse liver microsomal conversion of aflatoxin $B_1$ to aflatoxin ${B_1}-8,9-epoxide$.

• Microbiology and Biotechnology Letters
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• v.34 no.2
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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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.6
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• pp.1220-1225
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• 1999

Differences in carotenoid composition in the integument of Korean bittering, Cheilognathus signifer and bride bittering, Rhodeus ukekii which are Korean native fresh water fish were compared. Total ca rotenoid contents in the integument of wild Korean bittering was 2.11mg% and composed of 42.6% zeaxanthin, 12.1% diatoxanthin and 12.1% lutein epoxide which are predominant carotenoids and 10.3% cynthiaxanthin, 8.3% zeaxanthin epoxide, 6.4% lutein and 1.5% cryptoxanthin which are minor carotenoids. Total ca rotenoid contents in the integument of wild bride bittering was 4.99mg% during a spawning period but after the spawning period it was decreased to 4.17mg% and carotenoid composition of bride bittering during the spawning period was 46.7% zeaxanthin, 26.5% diatoxanthin and 12.3% lutein which are predominant carotenoids, and 6.2% zeaxanthin epoxide, 3.1% cynthiaxanthin, 2.9% cryptoxanthin and 0.7% canthax anthin which are minor carotenoids. These results indicated that the carotenoid composition of bride bittering during spawning period was very similar to that of Korean bittering and carotenoid composition of bride bittering after the spawning period was 30.5% diatoxanthin, 21.5% cynthiaxanthin and 16.8% zeaxanthin which are predominant carotenoids and 14.0% cryptoxanthin, 11.3% lutein and 3.4% can thaxanthin which are minor carotenoids, indicating that after the spawning period, the content of zeaxanthin was decreased while that of cryptoxanthin and cynthiaxanthin was increased as compared to that of the spawning period. Total carotenoid contents in Korean bittering and bride bittering was relatively higher than that in other species of cyprinidae whereas composition of the carotenoid was similar.

• KSBB Journal
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• v.22 no.3
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• pp.123-128
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• 2007

One drawback of conventional kinetic resolution of racemic epoxides by epoxide hydrolase (EH) is that the theoretical yield can never exceed 50%. This 50% limitation can be overcome by using enantioconvergent process, in which both enantiomers of the racemic epoxide are transformed via stereochemically matching pathways into a single enantiopure diol as the sole product in 100% theoretical yield. In order to make a single enantiopure vicinal diol, the two enantiomers of the racemic epoxide must be hydrolyzed with retention and inversion of configuration each other. The EHs should be enantio- and regiospecific at the same time. The enantioconvergent hydrolysis with EHs and relevant biotransformation for preparing enantiopure epoxides and vicinal diols with a high yield are reviewed.

• Applied Chemistry for Engineering
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• v.23 no.6
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• pp.599-603
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• 2012

The enantioselective hydrolysis of racemic styrene oxide in organic solvents was conducted using a recombinant E. coli expressing protein-engineered Mugil cephalus epoxide hydrolase (McEH). The volumetric total activity of the recombinant E. coli was enhanced 2.2-fold by IPTG induction at a mid-exponential growth phase. Among organic solvents with different log P values, isooctane was chosen based on the high activity and the enantioselectivity of McEH. Some lyoprotectants such as skim milk or sucrose enhanced the McEH activity. Enantiopure (S)-Styrene oxide with a 98% ee was obtained from the racemic styrene oxide with a 53.6% yield based on its theoretical yield in isooctane.

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.145-148
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• 2000

Large-scale resolution of epoxides by the yeast Rhodotorula glutinis was demonstrated in an aqueous/organic two-phase cascade membrane bioreactor. Due to the chemical instability and low solubility of epoxides in aqueous phases, an organic solvent was introduced into the reaction mixture in order to enhance resolution of epoxide. A cascade hollow-fiber membrane bioreactor was used (i) to minimize the toxicity of organic solvents towards the epoxide hydrolase of Rhodotorula glutinis, and (ii) to remove inhibitory amounts of formed diol from the yeast cell containing aqueous phase. Dodecane was selected as a suitable solvent and 1,2-epoxyhexane as a model substrate. By use of this membrane bioreactor, highly concentrated (0.9 M in dodecane) enantiopure (>98% ee) (S)-1,2-epoxyhexane (6.5 g, 30% yield) was obtained from its racemic mixture.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.435-438
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• 2003

Epoxide hydrolase(EH) catalyze the enantioselective hydrolysis of racemic epoxides to corresponding diols. A recombinant Pichia pastoris with EH from Rhodotorula glutinis has been constructed by reverse transcriptase-polymerase chain reaction(RT-PCR). The recombinant biocatalyst enantioselectively hydrolyze (R)-styrene oxide faster than (S)-enantiomer. The catalytic activity of recombinant biocatalyst was 7-fold higher than that of wild-type strain. The recombinant EH biocatalyst can be used for kinetic resolution for the production of enantiopure styrene oxide.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.4
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• pp.282-287
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• 2006

A Caulobacter crescentus epoxide hydrolase(CCEH) from a recombinant Escherichia coli was purified to homogeneity using a three-step procedure. The CCEH protein was purified 7.3-fold with a 22.9% yield in overalll activity. The optimal reaction temperature and pH were determined to be $37^{\circ}C$ and pH 8.0, respectively. The addition of 10%(v/v) dimethylsulfoxide as a cosolvent improved the enantioselectivity of CCEH for a batch kinetic resolution of racemic indene oxide.

• Biomolecules & Therapeutics
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• v.9 no.3
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• pp.143-155
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• 2001

Many attention has been focused on developing new chemotherapeutic agents for a treatment of cancer from natural products. From Carpesium divaricatum S. et Z. (Compositae), various monoterpenoid compounds were isolated and exhibited mild antitumor activity against human tumor cell lines. These facts prompted us to explore the structure-activity relationship of these compounds. The synthesis of monoterpenoid compound was accomplished by Fries rearrangement, Grignard reaction, elimination, allylic oxidation, esterification and epoxidation as key steps. The results of in vitro cytotoxicity (A549, SK-OV-3, SK-MEL-2, XF498, HCT15) of the synthesised compounds are as follows: First of all, epoxide moiety is prerequisite for cytotoxic activity in diester compound. Any kind of compounds with olefin or diol moiety instead of epoxide ring exhibited poor or mild cytotoxic activity respectively. Of o-acetoxy and isobutoxy epoxy esters, p-sub-stituted phenylacetate compounds exhibited high cytotoxic activities against SK-MEL-2 and HCT15.