• The Microorganisms and Industry
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• v.20 no.1
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• pp.18-22
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• 1994

효소는 반응을 효율적으로 촉진시킬 뿐만 아니라 기질 및 입체특이성을 갖고 있어 광학활성 화합물을 합성하는데 매우 유용한 촉매이다. 효소 반응은 일반적으로 수용액에서 진해오디지만, 유기 용매를 포함하는 용액에서도 가능하다. 대부분의 유기 화학 반응이 유기 용매에서 진행된다는 점을 생각할 때, 유기 용매에서 효소 반응을 이용한 유기합성이 갈수록 중요해지고 있다. 본 글에서는 유기 용매에서 사용가능한 대표적인 효소인 지질 가수분해 효소(lipase)를 이용한 유기합성에 대해서 간략히 기술하고자 한다.

• Journal of Life Science
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• v.2 no.4
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• pp.220-231
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• 1992

항체의 구조와 기능, 촉매항체의 이론적 배경과 방법론에 대하여, 특히 에스테르-아미드결합의 가수분해반응을 중심으로 기술하였다. 항체단백질은 분자량이 약 150kDa이며, 2가닥의 L사슬과 2가닥의 H사슬로 구성되어있다. 항체에 촉매작용을 도입하는 연구가 행해지고 있는데 대표적인 방법은 hapten에 대한 항체의 입체적 또는 전자적 상보성은 이용하는 것이고 둘째는 기질 특이적인 항체를 직접 화학수식 하든가 또는 부위 특이적 변이유발 등의 방법으로 촉매활성기를 도입하는 방법이다. 촉매항체의 매력은 합리적인 hapten의 설계로 원하는 촉매활성을 갖는 항체를 유도하는 데 있다.

• Journal of the Korean Chemical Society
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• v.21 no.2
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• pp.94-101
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• 1977

The NMR spectra of 2,4-disubstituted or 2,4,6-trisubstituted anisole derivative were examined to study the chemical shift of the ring proton signal. It was found that the chemical shift of the ring proton nearest to the 2-substituted group was influenced by the deshielding effect of the neighboring substituted groups in order of the Van der Waals radii of those groups. These observations were interpreted as a steric influence of 2-substituted group on the reactivity of the neighboring ring proton itself. The spectroscopical data were presented and the results were discussed with views of the above conceptions.

• Radiation Oncology Journal
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• v.20 no.2
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• pp.123-129
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• 2002

Purpose : The purpose of this study 띤as to determine the potential role of three-dimensional conformal radiotherapy (3D-CRT) in the treatment of primary unresectable hepatocellular carcinoma. The preliminary results on the efficacy and the toxicity of 3D-CRT are reported. Materials and Methods : Seventeen patients were enrolled in this study, which was conducted prospectively from January 1995 to June 1997. The exclusion criteria included the presence of extrahepatic metastasis, liver cirrhosis of Child-Pugh classification C, tumors occupying more than two thirds of the entire liver, and a performance status of more than 3 on the ECOG scale. Two patients were treated with radiotherapy only while the remaining 15 were treated with combined transcatheter arterial chemoembolization. Radiotherapy was given to the field including the tumor plus a 1.5 cm margin using a 3D-CRT technique. The radiation dose ranged from $36\~60\;Gy$ (median; 59.4 Gy). Tumor response was based on a radiological examination such as the CT scan, MR imaging, and hepatic artery angiography at $4\~8$ weeks following the completion of treatment. The acute and subacute toxicities were monitored. Results : An objective response was observed in 11 out of 17 patients, giving a response rate of $64.7\%$. The actuarial survival rate at 2 years was $21.2\%$ from the start of radiotherapy (median survival; 19 months). Six patients developed a distant metastasis consisting of a lung metastasis in 5 patients and bone metastasis in one. The complications related to 30-CRT were gastro-duodenitis $(\geq\;grade\;2)$ in 2 patients. There were no treatment related deaths and radiation induced hepatitis. Conclusion : The preliminary results show that 3D-CRT is a reliable and effective treatment modality for primary unresectable hepatocellular carcinoma compared to other conventional modalities. Further studies to evaluate the definitive role of the 3D-CRT technique in the treatment of primary unresectable hepatocellular carcinoma are needed.

• Korean Chemical Engineering Research
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• v.47 no.2
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• pp.179-184
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• 2009

Recent evolution of computer technology enhances the effectiveness of CFD(Computational Fluid Dynamics) analysis for the 3-dimensional complex transport phenomena including turbulent flows. Cheaper and easier than laser and ultra-sonic methods, the windows simulator name by CAMSI(Computer-Aided Management of Stereo Images) has been developed in order to implement the 3-dimensional image using a disparity histogram extracted from left and right stereo images. In our program using the area-based method, the matching pixel finding methods consist of SSD(Sum of Squared Distance), SAD(Sum of Absolute Distance), NCC(Normalized Correlation Coefficient) and MPC(Matching Pixel Count). On performing the program, stereo images on different window sizes for various matching pixel finding methods are compared reasonably. When the image has a small noise, SSD on small window size is more effective. Whereas there is much noise, NCC or MPC is more effective than SSD. CAMSI from the present study will be much helpful to implement the complex objects and to analyze 3-dimensional CFD around them.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.491-496
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• 2008

The microsomal epoxide hydrolase gene (referred to as mMCEH) of Mugil cephalus was cloned by PCR, and then inserted to pColdI and pET-21b(+) vector, respectively. The recombinant E. coli possessing the recombinant plasmids exhibited the enantioperference toward (R)-styrene oxide. When enantioselective kinetic resolutions were conducted with 20 mM racemic styrene oxide, enantiopure (S)-styrene oxide was obtained with high enantiopurity more than 99% enantiomeric excess (ee) and 24.50% yield by using the recombinant E. coli harboring pET-21b(+)/mMCEH.

• Applied Chemistry for Engineering
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• v.31 no.2
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• pp.187-192
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• 2020

(2S,3R)-3-hydroxyhomoserine lactone (HSL) has been used as a key intermediate for the synthesis of various biologically active compounds. In this study, we demonstrated an efficient synthesis of HSL via anti selective dihydroxylation of a protected vinyl glycine analog with an oxabicyclo[2.2.2]octyl orthoester (OBO) ester group. Because the acyclic conformation of the substrate was efficiently controlled by the bulky OBO ester group, a diastereoselectivity of > 10 : 1 was obtained in the dihydroxylation reaction without the use of a chiral reagent. By using this result, the target compound 1 can be obtained from commercially available N-Cbz-L-serine 2 in seven steps with an overall yeid of 34%. This result could be applied to the stereoselective synthesis of biologically active molecules containing a vicinal amino diol moiety.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.197-202
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• 2007

This research was basically carried out to extend the application of $CO_2$ absorption processes for flue-gas system, which are mainly applied to a reforming process in petro-chemical industries. In general, MEA absorbent has some problems in flue-gas treatment, such as, degradation, regeneration energy and absorption capacities. As we known, sterical hindered amine, typically AMP (2-amino 2-methyl 1-propanol), have a good potential to improve these problems. In this paper, the characteristics of $CO_2$ absorption in aqueous AMP solution were measured and compared with that of MEA. It has been found that the $CO_2$ absorption capacity in AMP is double than that of MEA in the low $CO_2$ partial pressure system such as flue-gas. Also, the equilibriums of $CO_2$-AMP system were partially suggested, which are essentially needed to design the absorption process.

• Journal of the Korean Chemical Society
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• v.36 no.4
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• pp.579-583
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• 1992

Stereoselective synthesis of farnesol, (2E, 6E)-3,7,11-trimethyldodeca-2,6,10-tiren-1-ol(1), was carried out using 5-bromo-2-methylpent-2-ene(2) as a starting material. After conversion of 5-bromo-2-methylpent-2-ene(2) to the corresponding iodide compound, 5-(4-methylpent-3-enyl)-2,3-dihydrofuran(4) was obtained by alkylation of 5-lithio-2,3-dihydrofuran with 5-iodo-2-methylpent-2-ene. Ni(0)-catalyzed coupling reaction of the dihydrofuran 4 with MeMgI was proceeded to give (3E)-4,8-dimethylnona-3,7-dien-1-ol(5) in 72% yield. The resultant homoallylic alcohol 5 was converted to the (5E)-6,10-dimethylundeca-5,9-dien-2-one(8) in 4 steps. Compound 8 was condensed with dimethylmethoxycarbonylmethylphosponate in benzene follwed by $NaBH_4$ reduction in EtOH to yield (2E, 6E)-3,7,11-trimethyldodeca-2,6,10-trien-1-ol(1). Ni(0)-catalyzed coupling reaction of MeMgI with dihydrofuran 4 was a key step in this synthesis of farnesol(1).

• Journal of the Korean Chemical Society
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• v.20 no.5
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• pp.380-390
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• 1976

The trends of forming a charge transfer complex have been studied for electron donors such as anisole, 4-chloroanisole, 2,4-dichloroanisole, 2-fluoro-4-chloroanisole, 2-bromo-4-chloroanisole, 2-iodo-4-chloroanisole, 2-fluoro-4,6-dichloroanisole, 2,4,6-trichloroanisole, 2-bromo-4,6-dichloroanisole, 2-iodo-4,6-dichloroanisole, and 2-iodo-4,5,6-trichloroanisole, and electron acceptors such as iodine and iodine monochloride in the carbon tetrachloride or the hexane solvent system. It was found that the formation of a charge transfer complex was influenced by the Van der Waals Radii of the 2-halogen atoms on the benzene ring and further the overall steric moiety of the molecule of the electron donor. These trends were also experienced in a system of chloroform and one of the prementioned electron donor by means of a nuclear magnetic resonance spectrometry. The spectrophotometrical data on the formation of the charge transfer complex were presented and the results were discussed with views of the steric structure of the 2-halogen atom on the benzene ring.