• Journal of Microbiology and Biotechnology
• /
• 제25권11호
• /
• pp.1810-1818
• /
• 2015

For the synthesis of various pharmaceuticals, chiral alcohols are useful intermediates. Among them, (R)-ethyl-4-chloro-3-hydroxybutanoate ((R)-ECHB) is an important building block for the synthesis of L-carnitine. (R)-ECHB is produced from ethyl-4-chloro-3-oxobutanoate (ECOB) by a reductase-mediated, enantioselective reduction reaction. The Saccharomyces cerevisiae YOL151W reductase that is expressed in Escherichia coli cells exhibited an enantioselective reduction reaction toward ECOB. By virtue of the C-terminal His-tag, the YOL151W reductase was purified from the cell-free extract using Ni²⁺-NTA column chromatography and immobilized onto Ni²⁺-magnetic microparticles. The physical properties of the immobilized reductase (Imm-Red) were measured using electron microscopy, a magnetic property measurement system, and a zeta potential system; the average size of the particles was approximately 1 μm and the saturated magnetic value was 31.76 emu/g. A neodymium magnet was used to recover the immobilized enzyme within 2 min. The Imm-Red showed an optimum temperature at 45℃ and an optimum pH at 6.0. In addition, Bacillus megaterium glucose dehydrogenase (GDH) was produced in the E. coli cells and was used in the coupling reaction to regenerate the NADPH cofactor. The reduction/oxidation coupling reaction composed of the Imm-Red and GDH converted 20 mM ECOB exclusively into (R)-ECHB with an e.e._p value of 98%.

• Bulletin of the Korean Chemical Society
• /
• 제35권2호
• /
• pp.436-440
• /
• 2014

The ${\alpha}$-Effect; Ground state; Transition state; Intramolecular H-bonding; Yukawa-Tsuno plot; Second-order rate constants for aminolysis of 2-chloro-4-nitrophenyl X-substituted-benzoates (1a-h) have been measured spectrophotometrically in 80 mol % $H_2O/20$ mol % DMSO at $25.0^{\circ}C$. The Br${\emptyset}$nsted-type plot for the reactions of 2-chloro-4-nitrophenyl benzoate (1d) with a series of primary amines curves downward, which has been taken as evidence for a stepwise mechanism with a change in rate-determining step (RDS). The Hammett plots for the reactions of 1a-h with hydrazine and glycylglycine are nonlinear while the Yukawa-Tsuno plots exhibit excellent linearity with ${\rho}_X=1.22-1.35$ and ${\gamma}= 0.57-0.59$, indicating that the nonlinear Hammett plots are not due to a change in RDS but are caused by stabilization of substrates possessing an electron-donating group (EDG) through resonance interactions between the EDG and C=O bond of the substrates. The ${\alpha}$-effect exhibited by hydrazine increases as the substituent X changes from a strong EDG to a strong electron-withdrawing group (EWG). It has been concluded that destabilization of hydrazine through the electronic repulsion between the adjacent nonbonding electrons is not solely responsible for the substituent dependent ${\alpha}$-effect but stabilization of the transition state is also a plausible origin of the ${\alpha}$-effect.

• 한국응용과학기술학회지
• /
• 제29권1호
• /
• pp.116-121
• /
• 2012

본 연구에서 황색 발색제는 피리딘 존재 하에 ${\alpha}$-pivaloyl-2-chloro-5-amino- acetaniline hydrogen chloride와 1-hexadecane sulfonyl chloride를 반응시켜 얻었다. 이 물질은 다양한 분석장비를 이용하여 녹는점, 원소분석기, 적외선분석기, 자외선분석기, 질량분석기로 확인하였다. 황색 발색제를 CD-3(발색현상주약)와 반응시키면 황색이 나타났다.

• Archives of Pharmacal Research
• /
• 제19권2호
• /
• pp.148-152
• /
• 1996

The efficient synthesis of 4-(2-thiazolyloxy)phenylalkanoic acids (10a-c), which are a potent antiinflammatory agent, was achieved in 5-6 steps starting from isopropoxybenzene and methyl $\alpha-chloro-\alpha-(methylthio)acetate (1)$. The key intermediate (4) was prepared by Friedel-Crafts reaction of isopropoxybenzene with (1) followed by desulfurization and the removal of isopropyl protector. Methyl 4-hydroxyphenylalkanoates (6, 8) were similarly obtained from alkylation of (3) and deprotection.

• 약학회지
• /
• 제38권5호
• /
• pp.504-510
• /
• 1994

A facile synthesis of 2-aryl-5-benzoxazolepropionic acid derivatives(1 0a-d), which are potent antiinflammatory agent, is reported. Methyl ${\alpha}$-(p-hydroxyphenyl)propionate(5) was prepared from Friedel-Crafts reaction of isopropoxy benzene with methyl ${\alpha}$-chloro-${\alpha}$-(methylthio) acetate(1), followed by desulfurization, methylation and clevage of ether bond. Compounds(10a-d) were made from(5) by a sequence of nitration, reduction, formation of benzoxazole ring, and hydrolysis in good yields, respectively.

• BMB Reports
• /
• 제29권2호
• /
• pp.111-115
• /
• 1996

A novel glutathione S-transferase from Pseudomonas sp. DJ77 was expressed in E. coli and purified by glutathione-affinity chromatography. The enzyme was composed of two identical subunits. The molecular size of the enzyme was 42 kDa by sephadex G-150 gel permeation chromatography and Mr of each subunit was 23 kDa by sodium dodecylsulfate-polyacrylamide gel electrophoresis. pI value of the enzyme was approximately 5.8 by isoelectric focusing. This enzyme showed the highest activity toward 1-chloro-2,4-dinitrobenzene as the electrophilic substrate. The relative activities toward p-nitrobenzyl chloride and 1,2-dichloro-4-nitrobenzene were 3.8% and 1.3% of the activity toward 1-chloro-2,4-dinitrobenzene, respectively. $K_m$ and $V_{max}$ values for 1-chloro-2,4-dinitrobenzene calculated by Lineweaver-Burk plot were 0.76 mM and $14.81\;{\mu}mol/min/mg$, respectively, and those for glutathione were 6.23 mM and $64.93\;{\mu}mol/min/mg$, respectively. The enzyme showed highest glutathione S-transferase activity at pH 8.0 and was stable between pH 6.0 and 9.0. The enzyme retained its activity up to $35^{\circ}C$ for 90 min but was unstable above $45^{\circ}C$.

• 대한화학회지
• /
• 제47권4호
• /
• pp.345-353
• /
• 2003

6-Chloro-3-methoxycarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline(5) 또는 3-methoxycarbonylmethylene- 6-nitro-2-oxo-1,2,3,4-tetrahydroquinoxaline(6)을 hydrazine hydrate와 반응시켜 3-hydrazinocarbonylmethylene-2-oxo-1,2,3,4-tetrahydroquinoxaline류(7, 8)를 합성하였다. 화합물 7 또는 8을 치환 벤즈알데히드류 및 헤테로고리 알데히드류와 반응시켜 quinoxaline류(9-14)를 각각 합성하였다. 합성한 화합물들은 dimethyl sulfoxide 용액에서 enamine형, methylene imine형 또는 enamine형, methylene imine형, enaminol형 사이에 토토머화 현상을 나타내었는데, 이들의 토토머 비를 1H NMR로서 측정하였다.

• 농약과학회지
• /
• 제8권3호
• /
• pp.175-183
• /
• 2004

신규한 벼 제초제 후보화합물 EK-3439 [3-chloro-2-[4-chlore-2-fluoro-5-(5-methyl-3-phenyl-4,5-dihydroisoxazol-5-yl-methoxy)-phenyl]-4,5,6,7-tetrahydro-2H-indazole]의 실용화를 위한 선택성과 토양 중 행동특성을 조사하였다. 직파 벼와 피 간의 선택성은 파종 후 4일 이내에 처리할 경우에 높게 나타났으며, 처리 후 12시간이 경과되면 환수되어도 제초효과의 변동이 일어나지 않았다. EK-5439와 oxadiazon은 모두 토양 중 이동 폭이 5cm/일의 누수 조건에서 1 cm 이내 이었다. EK-5439의 잔효 반감기는 6.1일 이었고, 동일 조건에서 oxadiazon은 9.6일 이었다. 토양 점토광물 bentonite에 의한 흡착은 oxadiazon에 비하여 상대적으로 큰 것으로 나타났으며 흡착력을 간단하게 평가하는 새로운 방법을 적용하였다.

• 대한화학회지
• /
• 제27권2호
• /
• pp.142-149
• /
• 1983

아세토니트릴용액중의 티안트렌 양이온 라디칼 과염소산 염(1)은 Cumene hydroperoxide(4), p-chlorocumene hydroperoxide(2), p-nitrocumene hydroperoxide(3)와 상온에서 반응한다. 이 반응의 공통 생성물로서 티안트렌을 얻었으며 4로 부터 5-(4'-hydroxyphenyl) thianthrenium perchlorate (5), 2로부터 5-(5'-chloro-2'-hydroxyphenyl) thianthrenium perchlorate (7)와 5-acetonylthianthrenium perchlorate (6), 그리고 3으로부터 6만을 얻었다. 이 반응의 양관계는 1의 2몰이 티안트렌 1몰과 티안트렌이움 염(또는 염들) 1몰을 생성한다. 1에 대한 친핵성 활성도는 페놀 > > p-클로로페놀 ${\sim}$아세톤 > > p-니트로페놀 순서임이 밝혀졌다. Hydroperoxide의 산촉매 불균일 분해반응외에도 소량의 균일분해 반응생성물이 3과 4로부터 생성됨을 알았다.

• Bulletin of the Korean Chemical Society
• /
• 제29권1호
• /
• pp.245-248
• /
• 2008