• 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.

• Applied Microscopy
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• v.13 no.1
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• pp.1-11
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• 1983

On the basis of the facts found in the previous report that chlorine destroyed cell membrane and stalk of Caulobacter crescentus and that the damaged cells abonrmally differentiated to elongate their stalks when the chlorinated cells were reincubated in fresh medium, it was suggested that there might be some ecological correlations between the level of water pollution and morphology and phsiology of Caulobacter cells. In order to determine such correlations in this study, 18 isolates of caulobacters were isolated from three sites of Musimcheon River which were gradually polluted by domestic sewages and 6 species were identified. Four cell types of bacteroid, vibroid, subvibroid, and fusiform is were isolated from the least polluted water at the rate of 43%, whereas only two cell types of bacteroid and vibroid were isolated from the more polluted waters at the rates of 7 and 10%, respectively. There was no significant difference in each species of Caulobacter isolateed from the gradually polluted river waters, except that abnormally long filamentous cells were occasionally observed in C. crescentus isolated from the most polluted water. Each species showed various responces to chlorine. The resistances of C. crescentus isolates to chlorine were proportionally correlated with the level of water pollution. When they were compared to C. crescentus CB 13 which had been adapted to laboratory enviroment, the C. cresucentus isolated from the most polluted water was more resistant to chlorine.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.32-36
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• 2006

The genome sequences from several microbes have led to the discovery of numerous open reading frames of unknown functionality. The putative bacterial epoxide hydrolase (EH) genes selected from the genome databases were examined for their activities toward various epoxides. Among the nine open reading frames (ORFs) from four microbial species, the ORF from Caulobacter crescentus showed an epoxide hydrolase activity. The kinetic resolution, using C. crescentus EH (CCEH) of the aryl epoxides such as styrene oxide, could be performed more efficiently than short aliphatic epoxides. The resolution of racemic indene oxide, which could previously be resolved only by fungal epoxide hydrolases, was effectively accomplished by CCEH.

• Microbiology and Biotechnology Letters
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• v.35 no.4
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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.

• Applied Chemistry for Engineering
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• v.18 no.3
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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.

• Journal of Microbiology and Biotechnology
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• v.18 no.1
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• pp.48-54
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• 2008

A putative ${\omega}$-aminotransferase gene, cc3143 (aptA), from Caulobacter crescentus was screened by bioinformatical tools and overexpressed in E. coli, and the substrate specificity of the ${\omega}$-aminotransferase was investigated. AptA showed high activity for short-chain ${\beta}$-amino acids. It showed the highest activity for 3-amino-n-butyric acid. It showed higher activity toward aromatic amines than aliphatic amines. The 3D model of the ${\omega}$-aminotransferase was constructed by homology modeling using a dialkylglycine decarboxylase (PDB ID: 1DGE) as a template. Then, the ${\omega}$-aminotransferase was rationally redesigned to increase the activity for 3-amino-3-phenylpropionic acid. The mutants N285A and V227G increased the relative activity for 3-amino-3-phenylpropionic acid to 3-amino-n-butyric acid by 11-fold and 3-fold, respectively, over that of wild type.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.625-625
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• 2005

• Proceedings of the Korean Society of Life Science Conference
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• 2005.09a
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• pp.88-88
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• 2005

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.476-476
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• 2003

• Proceedings of the Korean Society for Bioinformatics Conference
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• 2005.09a
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• pp.339-343
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• 2005

Boolean networks(BN) construction is one of the commonly used methods for building gene networks from time series microarray data. However, BN has two major drawbacks. First, it requires heavy computing times. Second, the binary transformation of the microarray data may cause a loss of information. This paper propose two methods using liner regression to construct gene regulatory networks. The first proposed method uses regression based BN variable selection method, which reduces the computing time significantly in the BN construction. The second method is the regression based network method that can flexibly incorporate the interaction of the genes using continuous gene expression data. We construct the network structure from the simulated data to compare the computing times between Boolean networks and the proposed method. The regression based network method is evaluated using a microarray data of cell cycle in Caulobacter crescentus.