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Production of chiral β-amino acids using ω-transaminase from Burkholderia graminis
Mathew, S.,Bea, H.,Nadarajan, S.P.,Chung, T.,Yun, H. Elsevier Science Publishers 2015 Journal of biotechnology Vol.196 No.-
<P>Optically pure beta-amino acids are of high pharmacological significance since they are used as key ingredients in many physiologically active compounds. Despite a number of enzymatic routes to these compounds, an efficient synthesis of beta-amino acids continues to pose a major challenge for researchers. omega-Transaminase has emerged as an important class of enzymes for generating amine compounds. However, only a few omega-transaminases have been reported so far which show activity towards aromatic beta-amino acids. In this study, (S)-omega-transaminase from Burkholderia graminis C4D1M has been functionally characterized and used for the production of chiral aromatic beta-amino acids via kinetic resolution. The enzyme showed a specific activity of 3.1 U/mg towards rac-beta-phenylalanine at 37 degrees C. The K-m and K-cat values of this enzyme towards rac-beta-phenylalanine with pyruvate as the amino acceptor were 2.88 mM and 91.57 min(-1) respectively. Using this enzyme, racemic beta-amino acids were kinetically resolved to produce (R)-beta-amino acids with an excellent enantiomeric excess (> 99%) and similar to 50% conversion. Additionally, kinetic resolution of aromatic beta-amino acids was performed using benzaldehyde as a cheapamino acceptor. (C)2015 Elsevier B.V. All rights reserved.</P>
Thakur, Santosh Singh,Chen, Shu-Wei,Li, Wenji,Shin, Chang-Kyo,Kim, Seong-Jin,Koo, Yoon-Mo,Kim, Geon-Joong Elsevier 2006 Journal of organometallic chemistry Vol.691 No.9
<P><B>Graphical abstract</B></P><P>Dinuclear chiral salen complexes bearing Lewis acid of group 13 metals catalyze asymmetric ring opening of various terminal epoxides with myriad of nucleophiles via kinetic resolution. The complexes are also found to be active for asymmetric cyclization reaction too.</P><ce:figure></ce:figure> <P><B>Abstract</B></P><P>A new dinuclear chiral Co(salen) complexes bearing group 13 metals have been synthesized and characterized. The easily prepared complexes exhibited very high catalytic reactivity and enantioselectivity for the asymmetric ring opening of epoxides with H<SUB>2</SUB>O, chloride ions and carboxylic acids and consequently provide enantiomerically enriched terminal epoxides (>99% ee). It also catalyzes the asymmetric cyclization of ring opened product, to prepare optically pure terminal epoxides in one step. The homogeneous dinuclear chiral Co(salen) have been covalently immobilized on MCM-41. The potential benefits of heterogenization include facilitation of catalyst separation and recyclability requiring very simple techniques. The system described is very efficient.</P>
Kinetic resolution of rac-amines using furfural as amino acceptor
김준성,신종식 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.1
Optically pure amines are important building blocks for pharmaceutical drugs. ω-Transaminase (ω-TA) is an attractive enzyme to prepare chiral amines because of its high enantioselectivity and regioselectivity. Here, we prepared optically pure amines by ω-TA-mediated kinetic resolution of rac-amines using furfural, one of agricultural byproducts from biomass, as an amino acceptor instead of pyruvate. S- and R-selective ω-TAs from Ochrobactrum anthropi (OATA) and Aspergillus fumigatus (AFTA), respectively, showed high activity toward furfural among six ω-TAs. Structurally diverse amines were prepared with high enantiopurity (>99% ee) by kinetic resolution using OATA and AFTA.
Kinetic resolution of amines by (R)-selective omega-transaminase from Mycobacterium vanbaalenii
신기영,Sam Mathew,윤형돈 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.23 No.-
Recently (R)-selective v-transaminase ((R)-v-TAMV) from Mycobacterium vanbaalenii was discovered and utilized for the asymmetric synthesis of (R)-amines from its corresponding ketones. In this study, (R)-v-TAMV was used for the kinetic resolution of racemic amines to produce (S)-amines. (R)-v-TAMV showed very low product inhibition by ketone product (acetophenone), which is beneficial for carrying out the kinetic resolution of racemic amines with high concentration. 100 mM racemic amines were successfully resolved into (S)-amines (>99% ee) by (R)-v-TAMV with pyruvate. In addition, the kinetic resolution of a-MBA was successfully carried out by using acetone as an amino acceptor which is cheaper than pyruvate.
Chemoenzymatic Dynamic Kinetic Resolution of Alcohols and Amines
Lee, Jin Hee,Han, Kiwon,Kim, Mahn-Joo,Park, Jaiwook WILEY-VCH Verlag 2010 European journal of organic chemistry Vol.2010 No.6
<P>Dynamic kinetic resolution (DKR) is an attractive process for the transformation of racemic mixtures into optically active compounds. For successful DKR, efficient racemization is required while the kinetic resolution is proceeding. This Microreview mainly summarizes the recent developments in the DKR of alcohols and amines, based on metal-catalyzed racemization and enzymatic acylation in a single reaction vessel. Related reactions involving precursors of alcohols and amines such as ketones, enol acetates, and ketoximes are also described. Reaction conditions are arranged according to racemization catalysts, and substrates employed in the DKR are tabulated. Suggested mechanisms for metal-catalyzed racemizations are also summarized.</P> <B>Graphic Abstract</B> <P>Dynamic kinetic resolution (DKR) is an attractive process for the production of optically active compounds from racemic mixtures. Combinations of the processes of metal-catalyzed racemization and enzymatic acylation in one-pot fashion have shown the potential of DKR of alcohols and amines. This Microreview summarizes developments in and the scope of chemoenzymatic DKR. <img src='wiley_img/1434193X-2010-2010-6-EJOC200900935-fig000.gif' alt='wiley_img/1434193X-2010-2010-6-EJOC200900935-fig000'> </P>
Asymmetric Synthesis of Biaryl Diols via Dynamic Kinetic Resolution
Cho Jeonghun,Kim Kyungwoo,Park Jaiwook,Kim Mahn‐Joo 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.7
We have developed a protocol incuding dynamic kinetic resolution as the key step for the asymmetric synthesis of biaryl diol stereoisomers. The two aryl alkanols as the starting materials were cross-coupled by palladium catalysis to give dl- and meso-diol, which were then subject to chemoenzymatic dynamic kinetic resolution (DKR) for the transformation into single stereoisomeric diol diester. Diol diester was finally deacylated to give the corresponding biaryl diol stereoisomer. The chemoenzymatic DKR was performed with a ruthenium-based racemization catalyst and a (R)-selective lipoprotein lipase. Total 17 (R, R)-diols including 7 C2-symmetric diols were synthesized with excellent enantiopurities (>99% ee).
저온 분사 코팅 공정에서 충돌속도에 따른 CuNiTiZr 벌크 비정질 소재의 활성화 에너지와 결정화 거동 분석
윤상훈(Sanghoon Yoon),배규열(Gyuyeol Bae),김정환(Junghwan Kim),이창희(Changhee Lee) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.6
In this paper, nanocrystallization of CuNiTiZr bulk metallic glass (BMG) subjecting to a k inetic spraying, dependent on impact velocity, was investigated by numerical and experimental approaches. The crystallization fraction and nucleation activation energy of initial feedstock and as-deposited coating were estimated by DSC and Kissinger method, respectively. The results of numerical modeling and experiment showed that the crystalline fraction and nucleation activation energy in BMG coatings were depended on kinetic energy of incident particle. Upon impact, the conversion of particle kinetic energy leads to not only decreasing free energy barrier but also increasing the driving force for an amorphous to crystalline phase transformation. The nanocrystallization of BMGs is associated with the strain energy delivered by a plastic deformation with a high strain rate.
Kinetic Resolutions by Enantioselective Pauson–Khand-Type Reaction
Kim, Dong Eun,Kwak, Jaesung,Kim, In Su,Jeong, Nakcheol WILEY-VCH Verlag 2009 Advanced Synthesis & Catalysis Vol. No.
<P>A kinetic resolution of 1-arylallyl propargyl ethers by enantioselective Pauson–Khand-type reaction catalysts was successfully carried out. While cationic rhodium(I) with a BINAP-based ligand having an electron-deficient phosphine is the choice for the slow reacting substrates, neutral iridium(I) with a BINAP-based ligand possessing an electron-rich phosphine provided excellent results for the more reactive substrates.</P> <B>Graphic Abstract</B> <P> <img src='wiley_img/16154150-2009-351-1-2-ADSC200800657-content.gif' alt='wiley_img/16154150-2009-351-1-2-ADSC200800657-content'> </P>
Yoon, S.,Bae, G.,Xiong, Y.,Kumar, S.,Kang, K.,Kim, J.J.,Lee, C. Elsevier Science 2009 Acta materialia Vol.57 No.20
Nanocrystallization of CuNiTiZr bulk metallic glass (BMG) subjected to kinetic spraying with variable impact velocities was investigated through numerical and experimental approaches. The fraction of crystallization and activation energy of the initial feedstock and as-deposited coatings were estimated through differential scanning calorimetry and the Kissinger method, respectively. The numerical and experimental results showed that the fraction of crystallinity and activation energy for nucleation in BMG coatings is strongly related to the kinetic energy of the impacting particles. Upon high-velocity impact, the kinetic energy of the particle led to a decrease in the free energy barrier and an increase in the driving force for the amorphous-to-crystalline phase transformation. Microstructure observation revealed that the nanocrystallization of the BMG in the kinetic spray process was associated with the strain energy delivered by plastic deformation using a high strain rate.