• Clean Technology
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• v.22 no.2
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• pp.75-81
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• 2016

As the quality of life has improved, the desire for the safety and quality of the foods and drugs has been gradually increasing. For safety and quality management in foods, drugs, health management, agriculture, environmental conservation, and the industrial fields, the demand for quickly and accurately measuring various chemicals has been increasing. As well, the desire for self-diagnosis of one's own health state and self-examining the safety of environment has been gradually increasing. Optical Isomers can have very different physiological effects on human beings. One isomer can exhibit desirable pharmacological, pharmacodynamic, pharmacokinetic and physiological properties, while the other isomer can exhibit undesirable and toxic properties toward living organisms, especially human beings. And they can exhibit different activities in chemical and biotechnological processes. Although the majority of commercially available drugs are now both synthetic and chiral materials, a most chiral drugs are still marketed as racemic drugs. Thus, to avoid possible undesirable side effects from chiral drugs, more effective methods for separating and recognizing chiral compounds are urgently needed. In this report, we investigated the overall developing trends of the chiral drug separation and analysis technology by using molecular recognition.

• KSBB Journal
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• v.25 no.5
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• pp.449-452
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• 2010

L-Thyroxine possessing a chiral center, the naturally occurring thyroid hormone has been used for the treatment of thyroid dysfunctions and marketed as levothyroxine (L-thyroxine) sodium salt. In this study, after extraction of levothyroxine tablet as a pre-treatment process, direct enantiomer separation of thyroxine on crown ether derived chiral columns for determination of optical purity was performed using reversed mobile phase with acid additive. The chromatographic method developed in this study was applied in the determination of optical purity of several current domestic and foreign commercialized levothyroxine tablets. Optical purity values of these commercialized L-thyroxine sodium tablets except one were higher than 99 percents.

• The Microorganisms and Industry
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• v.20 no.1
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• pp.11-17
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• 1994

본 고에서는 리파제를 이용한 키랄약품의 합성 및 새로운 합성기술을 요약하고자 한다.

• Journal of the Korean Chemical Society
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• v.49 no.3
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• pp.283-287
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• 2005

• KSBB Journal
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• v.19 no.4
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• pp.274-283
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• 2004

Six lumbrokinase (LK) fractions from Lumbricus rubellus lysates were purified by a series of column chromatographies. The molecular weights of the six LK fractions appeared to range from 24.6 to 33.1 kDa. In the experimental model of rat venous thrombosis, the thrombus weight and PAI activity decreased significantly when the LK was administered orally. However, the activities of APTT, PT and plasmin showed a significant increase. The aggregation of rat platelets pretreated with various LK doses was inhibited by thrombin, and the MDA generation decreased. The rat thoracic aorta and mesentric arteries contracted with phenylephrine relaxed due to the treatment of the LK fractions. These results suggest that the fibrinolytic effects of LK were mediated not only by proteolytic activity, but also by the inhibition of platelet agregation and the relaxation of blood vessels. It is concluded that the LK may be useful as a hemolytic agent for treatment of fibrin clot.

• KSBB Journal
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• v.19 no.3
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• pp.215-220
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• 2004

A variety of solid bases such as inorganic bases, basic anion exchange resins, and resin-bound bases were tested as a catalyst for racemization of (S)-naproxen 2,2,2-trifluoroethyl thioester in isooctane at 45$^{\circ}C$. Among the various bases, DIAIOM WA30, which is a weakly basic anion exchange resin with a tertiary amine based on a highly porous type styrene-divinylbenzene copolymer, showed the highest catalytic activity. The second-order interconversion constant of DIAION WA30 was 8.6${\times}$10$\^$-4/ mM$\^$-1/h$\^$-1/ and about 3 times higher than that of trioctylamine under the same conditions. The rate of DIAION WA30-catalyzed racemization decreased with increasing an amount of water added to the reaction medium. Lipase-catalyzed kinetic resolution of racemic naproxen 2,2,2-trifluoroethyl thioester was successfully carried out under in situ racemization of substrate with DIAION WA30 in isooctane at 45$^{\circ}C$. More than 60% conversion and 99% enantiomeric excess for the desired (S)-naproxen product were obtained. Furthermore, such a solid base catalyst could be easily separated and reused in contrast to trioctylamine.

• Microbiology and Biotechnology Letters
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• v.34 no.3
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• pp.204-210
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• 2006

Ethyl (S)-4-chloro-3-hydroxybutyrate is a useful intermediate for the synthesis of Atorvastatin, a chiral drug to hypercholesterolemia. In this research, two 4-chloro-3-hydroxybutyro-nitrile-degrading strains were isolated from soil sample. They were identified as Rhodococcus erythropolis strains by 16S rRNA analysis. The nitrile-degrading enzyme(s) were suggested to be nitrile hydratase and amidase rather than nitrilase from the result of thin layer chromatography analysis. The corresponding genes were obtained by PCR cloning method. The predicted protein sequences had identities more than 96% with nitrile hydratase ${\alpha}-subunit$, nitrile hydratase ${\beta}-subunit$, and amidase of R. erythropolis. The 4-chloro-3-hydroxybutyronitrile-hydrolyzing activities in both strains were increased dramatically by ${\varepsilon}-caprolactam$ which was known as good inducer for nitrile hydratase. Both intact cells and cell-free extract could hydrolyze the nitrile compound. So, the intact cell and the enzymes could be used as potential biocatalyst for the production of 4-chloro-3-hydroxybutyric acid.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.118-124
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• 2009

Esterase EM2L8 gene isolated from deep sea sediment was expressed in Escherichia coli BL21 (DE3) and the esterase activity of the cell-free extract was assayed using p-nitrophenyl butyrate-spectrophotometric method. Its optimum temperature was $40-45^{\circ}C$ and 45% activity of the maximum activity was retained at $15^{\circ}C$. The activation energy at $15-45^{\circ}C$ was calculated to be 4.9 kcal/mol showing that esterase EM2L8 was a typical cold-adapted enzyme. Enzyme activity was maintained for 6 h and 4 weeks at $30^{\circ}C$ and $4^{\circ}C$, respectively. When each ethanol, methanol, and acetone was added to the reaction mixture to 15% concentration, enzyme activity was maintained. In the case of DMSO, enzyme activity was kept up to 40% concentration. (S)-4-Chloro-3-hydroxy butyric acid is a chiral intermediate for the synthesis of Atorvastatin, a hyperlipemia drug. When esterase EM2L8 (40 U) was added to buffer solution (1.2 mL, pH 9.0) containing ethyl-(R,S)-4-chloro-3-hydroxybutyrate (38 mM), it was hydrolyzed into 4-chloro-3-hydroxy butyric acid with a rate of $6.8\;{\mu}mole/h$. The enzyme hydrolyzed (S)-substrate more rapidly than (R)-substrate. When conversion yield was 80%, e.e.s value was 40%. When DMSO was added, hydrolysis rate increased to $10.4\;{\mu}mole/h$. The plots of conversion yield vs e.e.s in the presence or absence of DMSO were almost same, implying that the reaction enantioselectivity was not changed by the addition of DMSO. Taken together, esterase EM2L8 had high activity and stability at low temperatures as well as in various organic solvents/aqueous solutions. These properties suggested that it could be used as a biocatalyst in the synthesis of useful pharmaceuticals.