• Journal of Microbiology and Biotechnology
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• 제23권10호
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• pp.1395-1402
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• 2013

Reductases convert some achiral ketone compounds into chiral alcohols, which are important materials for the synthesis of chiral drugs. The Saccharomyces cerevisiae reductase YOR120W converts ethyl-4-chloro-3-oxobutanoate (ECOB) enantioselectively into (R)-ethyl-4-chloro-3-hydroxybutanoate ((R)-ECHB), an intermediate of a pharmaceutical. As YOR120W requires NADPH as a cofactor for the reduction reaction, a cofactor recycling system using Bacillus subtilis glucose dehydrogenase was employed. Using this coupling reaction system, 100 mM ECOB was converted to (R)-ECHB. A homology modeling and site-directed mutagenesis experiment were performed to determine the NADPH-binding site of YOR120W. Four residues (Q29, K264, N267, and R270) were suggested by homology and docking modeling to interact directly with 2'-phosphate of NADPH. Among them, two positively charged residues (K264 and R270) were experimentally demonstrated to be necessary for NADPH 2'-phosphate binding. A mutant enzyme (Q29E) showed an enhanced enantiomeric excess value compared with that of the wild-type enzyme.

• 대한화학회지
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• 제48권6호
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• pp.599-608
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• 2004

유연격자와 메타크릴로일 기 사이에 도입된 벤젠 고리와 메소겐 구조의 말단에 연결된 키랄 중심을 갖는 새로운 두 계열의 메타크릴레이트 단량체를 합성하였다. 이 두 계열에서 유연격자와 메소겐 기의 길이 변화에 따른 액정형성에 대한 효과를 조사하였다. 첫 번째 계열의 화합물들은 합성과정에서 얻어진 중간물질이나 최종물질에서 액정성을 보이지 않았다. 그러나 두 번째 계열에서는 중간물질 뿐만아니라 최종물질에서도 액정성을 보였다.

• Plant Resources
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• 제6권1호
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• pp.81-88
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• 2003

Higenamine [1-(4-hydroxy-6, 7-dihydroxy-l, 2, 3, 4-tetrahydroisoquinoline) is a cardiotonic constituent of Aconiti tuber, one of the most widely prescribed oriental medicines. S-(-)higenamine was reported to have a stronger cardiotonic activity than R-(+)-higenamine and known as a central intermediate in the biosynthesis of various benzyl isoquionoline alkaloids in plants. The separation of higenamine enantiomers has been accomplished with capillary electrophoresis using cyclodextrins (CDs) as chiral selectors. Good resolution of this enantiomers was obtained using a 50 mM sodium phosphate buffer containing hydroxypropyl $\beta$-CDs using 27 cm fused silica capillary (50${\mu}{\textrm}{m}$ i.d., 20 cm to detector) at 25 $^{\circ}C$. With the electric field of 340 V/cm, the separation time of higenamine enantiomers was less than 6 min. Under this optimum conditions, the relative standard deviations of migration time and peak area were less than 1.6% and 3.2%. A 512-channel diode array detector was confirmed for the higenamine. The detection limits (S/N = 3) of these enantiomers are $1.5mutextrm{m}$/mL. We confirmed the chiral form of higenamine in medicinal plants.

• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.409-414
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• 2012

Xanthorrhizol is a bisabolane type of natural sesquiterpene, the major component of essential oils of Curcuma xanthorrhiza. 2-(3-Methoxy-4-methylphenyl)propan-1-ol and 2-(3-hydroxy-4-methyl phenyl)propan-1-ol could be essential building block for enantioselective synthesis of xanthorrhizol. Enantioselective (c = 53%, E = $80{\pm}3$) for R-(+)-2-(3-hydroxy-4-methylphenyl) propan-1-ol and (c = 58%, E = $27{\pm}1$) for R-(+)-2-(3-methoxy-4-methylphenyl) propan-1-ol resolution processes were developed via lipase-catalyzed reaction. We found lipase Aspergillus oryzae (AOL) and Porcine pancreas (PPL) are selective to transesterification and hydrolysis in organic and aqueous phase. Modified demethylated substrate is appropriate for enantioselective hydrolysis reaction without any additives. Enantiopure chiral alcohol was crystallized from ethyl acetate/n-hexane co-solvent system. Gram scale resolved chiral intermediate will facilitate the synthesis of the unnatural S-(+)-xanthorrhizol, the corresponding isomer of the natural one.

• Bulletin of the Korean Chemical Society
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• 제10권6호
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• pp.572-577
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• 1989

Using the low valent titanium induced carbonyl-carbonyl coupling reaction, it was attempted to synthesize sterically hindered 17-membered cyclic chiral host 2. The semifinal dialdehyde 12 was obtained through 11 step reactions beginning from p-tert-butylphenol and dibenzofuran. When dialdehyde 12 was treated with $TiCl_3-Zn/Cu,$ only intermolecularly coupled dimer 14 was obtained instead of intramolecularly coupled cyclic alkene 2. The mechanistic consideration leading to 14 was discussed and the cation binding properties of dimer 14 and dicarboxylic intermediate 13 was reported, which implies the significance of the principle of preorganization of host's binding sites prior to complexation.

• 대한화학회지
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• 제39권2호
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• pp.94-102
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• 1995

모세관 기체크로마토그래피에 의한 cyclodextrin 정지상들(PH-${\beta}$-CD, DA-${\beta}$-CD, TA-${\gamma}$-CD)을 이용하여 라세미 알코올들과 그 유도체들의 분리를 연구하였다. 실험에 사용한 모든 알코올들은 trifluoro acetic anhydride, acetic anhydride, trichloro acetic anhydride를 써서 유도화하였다. 거울상체들의 분리선택성은 acylation 시약의 형태에 상당히 의존하는 것을 알았다. 알코올과 그 유도체들의 광학분활에 대한 최상의 실험조건은 용질분자들의 극성에 따라 다르다. 그리고 키랄분리에 관해서 온도, 컬럼이 극성, 수소 결합력, 알코올과 CD 정지상의 입체효과 등의 의존에 관한 연구를 행하였다. 키랄 인식 기구는 키랄 정지상의 종류에 의존하지 않고, 라세미 알코올의 유도체화에 의존하는 것으로 나타났다.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2213-2218
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• 2012

Efficient synthetic routes were developed to prepare a sizable amount (4-15 grams) of the chiral epoxides 4-6 as versatile intermediates for the synthesis of aspartyl protease inhibitors of therapeutic interest such as HIV protease and ${\beta}$-secretase. Oxidative cleavage of the C(2)-C(3) double bond of L-ascorbic acid followed by functional group manipulation led to the preparation of the epoxide 10, which was opened with an azide to yield a common aziridine intermediate 12. Through opening of the aziridine ring of 12 with either a carbon or a sulfur nucleophile, chiral epoxide precursors 4-6 could be prepared for various HIV protease inhibitors. Except for the final low melting epoxides 5 and 6, all intermediates were obtained as crystalline solids, thus the synthetic pathway can be easily applied to a large-scale synthesis of the chiral epoxides.

• Bulletin of the Korean Chemical Society
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• 제14권1호
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• pp.86-91
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• 1993

A synthetic route to (+)-isocarbacyclin starting from (-)-tricyclo[3.3.0.0$^{2.8}$]octan-3-one 6 is described. The key intermediate 4 has been synthesized from 6 by a sequential introduction of methoxycarbonyl group at C-12 and the oxygen functionality at C-9${\alpha}$(PG numbering) for the construction of ${\alpha}-and\;{\omega}$-side chain, and then converted to isocarbacyclin methyl ester 2.

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

• Journal of Microbiology and Biotechnology
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• 제20권9호
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• pp.1300-1306
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• 2010

Ethyl (R, S)-4-chloro-3-hydroxybutanoate (ECHB) is a useful chiral building block for the synthesis of L-carnitine and hypercholesterolemia drugs. The yeast reductase, YOL151W (GenBank locus tag), exhibits an enantioselective reduction activity, converting ethyl-4-chlorooxobutanoate (ECOB) exclusively into (R)-ECHB. YOL151W was generated in Escherichia coli cells and purified via Ni-NTA and desalting column chromatography. It evidenced an optimum temperature of $45^{\circ}C$ and an optimum pH of 6.5-7.5. Bacillus subtilis glucose dehydrogenase (GDH) was also expressed in Escherichia coli, and was used for the recycling of NADPH, required for the reduction reaction. Thereafter, Escherichia coli cells co-expressing YOL151W and GDH were constructed. After permeablization treatment, the Escherichia coli whole cells were utilized for ECHB synthesis. Through the use of this system, the 30 mM ECOB substrate could be converted to (R)-ECHB.