- Co-immobilized Whole Cells with ω-Transaminase and Ketoreductase Activities for Continuous-Flow Cascade Reactions
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An improved sol–gel process involving the use of hollow silica microspheres as a supporting additive was applied for the co-immobilization of whole cells of Escherichia coli with Chromobacterium violaceum ω-transaminase activity and Lodderomyces elongisporus with ketoreductase activity. The co-immobilized cells with two different biocatalytic activities could perform a cascade of reactions to convert racemic 4-phenylbutan-2-amine or heptan-2-amine into a nearly equimolar mixture of the corresponding enantiomerically pure R amine and S alcohol even in continuous-flow mode. The novel co-immobilized whole-cell system proved to be an easy-to-store and durable biocatalyst.
- Nagy-Gy?r, László,Abaházi, Emese,Bódai, Viktória,Sátorhelyi, Péter,Erdélyi, Balázs,Balogh-Weiser, Diána,Paizs, Csaba,Hornyánszky, Gábor,Poppe, László
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p. 1845 - 1848
(2018/09/10)
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- Biocatalytic Racemization Employing TeSADH: Substrate Scope and Organic Solvent Compatibility for Dynamic Kinetic Resolution
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Racemization in combination with a kinetic resolution is the base for a dynamic kinetic resolution (DKR). Biocatalytic racemization was successfully performed for a broad scope of sec-alcohols by employing a single alcohol dehydrogenase (ADH) variant from Thermoanaerobacter pseudoethanolicus (formerly T. ethanolicus; TeSADH W110A I86A C295A). The catalyst employed as a lyophilized whole cell preparation or cell free extract, which tolerated various non-water miscible organic solvents under micro-aqueous or two-phase conditions, whereby cyclohexane and n-hexane suited best. Various concepts for combining the enzymatic racemization with an enzymatic kinetic resolution to achieve overall a bis-enzymatic DKR were evaluated. A proof of concept showed a successful DKR with racemization in aqueous phase combined with acylation in the organic phase.
- Pop?oński, Jaros?aw,Reiter, Tamara,Kroutil, Wolfgang
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p. 763 - 768
(2018/02/27)
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- ALKANE OXIDATION BY MODIFIED HYDROXYLASES
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This invention relates to modified hydroxylases. The invention further relates to cells expressing such modified hydroxylases and methods of producing hydroxylated alkanes by contacting a suitable substrate with such cells.
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Paragraph 0323; 0324
(2016/02/16)
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- Discrimination of the prochiral hydrogens at the C-2 position of n-alkanes by the methane/ammonia monooxygenase family proteins
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The selectivity of ammonia monooxygenase from Nitrosomonas europaea (AMO-Ne) for the oxidation of C4-C8n-alkanes to the corresponding alcohol isomers was examined to show the ability of AMO-Ne to recognize the n-alkane orientation within the catalytic site. AMO-Ne in whole cells produces 1- and 2-alcohols from C4-C8n-alkanes, and the regioselectivity is dependent on the length of the carbon chain. 2-Alcohols produced from C4-C7n-alkanes were predominantly either the R- or S-enantiomers, while 2-octanol produced from n-octane was racemic. These results indicate that AMO-Ne can discriminate between the prochiral hydrogens at the C-2 position, with the degree of discrimination varying according to the n-alkane. Compared to the particulate methane monooxygenase (pMMO) of Methylococcus capsulatus (Bath) and that of Methylosinus trichosporium OB3b, AMO-Ne showed a distinct ability to discriminate between the orientation of n-butane and n-pentane in the catalytic site.
- Miyaji, Akimitsu,Miyoshi, Teppei,Motokura, Ken,Baba, Toshihide
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p. 8261 - 8270
(2015/08/03)
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- A novel P450-based biocatalyst for the selective production of chiral 2-alkanols
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A P450 monooxygenase from Nocardia farcinica (CYP154A8) catalyses the stereo- and regioselective hydroxylation of n-alkanes, still a challenging task in chemical catalysis. In a biphasic reaction system, the regioselectivity for the C2-position of C7-C9 alkanes was over 90%. The enzyme showed strict S-selectivity for all tested substrates, with enantiomeric excess (ee) of up to 91%. This journal is the Partner Organisations 2014.
- Von Bühler, Clemens J.,Urlacher, Vlada B.
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supporting information
p. 4089 - 4091
(2014/04/03)
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- In vitro double oxidation of n-heptane with direct cofactor regeneration
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A novel concept for the direct oxidation of cycloalkanes to the corresponding cyclic ketones in a one-pot synthesis in water with molecular oxygen as sole oxidizing agent was reported recently. Based on this concept we have developed a new strategy for the double oxidation of n-heptane to enable a biocatalytic resolution for the direct synthesis of heptanone and (R)-heptanols in a one-pot reaction. The bicatalytic cascade employs an NADH driven P450 BM3 monooxygenase variant (WTNADH, 19A12NADH or CM1 NADH) and an (S)-enantioselective alcohol dehydrogenase (RE-ADH). In the initial step n-heptane is hydroxylated under consumption of NADH to produce (R/S)-heptanol. In the second oxidation step the (S)-heptanol enantiomers are transformed to the corresponding ketones, reducing and thereby regenerating the cofactor. Characterization of initial hydroxylation step revealed high turnover frequencies (TOF) of up to 600 min-1, as well as high coupling efficiencies using NADH as cofactor (up to 44%). In the cascade reaction a nearly 2-fold improved product formation was achieved, compared to the single hydroxylation reaction. The total product concentration reached 1.1 mM, corresponding to a total turnover number (TTN) of 2500. Implementation of an additional cofactor regeneration system (D-glucose/glucose dehydrogenase) enabled a further enhancement in product formation with a total product concentration of 1.8 mM and a TTN of 3500. Copyright
- Mueller, Christina A.,Akkapurathu, Beneeta,Winkler, Till,Staudt, Svenja,Hummel, Werner,Groeger, Harald,Schwaneberg, Ulrich
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supporting information
p. 1787 - 1798
(2013/07/19)
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- Preparation and properties of xerogels obtained by ionic liquid incorporation during the immobilization of lipase by the sol-gel method
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Lipase from Pseudomonas fluorescens (Amano AK) has been immobilized by the sol-gel method using tetramethoxysilane and trimethoxysilanes with alkyl or aryl groups as precursors and ionic liquids as immobilization additives. Room temperature ionic liquids
- Zarcula, Cristina,Corici, Livia,Croitoru, Ramona,Ursoiu, Anca,Peter, Francisc
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experimental part
p. 79 - 86
(2010/10/19)
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- A thermodynamic study of the ketoreductase-catalyzed reduction of 2-alkanones in non-aqueous solvents
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Equilibrium constants K have been measured for the reactions (2-alkanone + 2-propanol = 2-alkanol + acetone), where 2-alkanone = 2-butanone, 2-pentanone, 2-hexanone, 2-heptanone, and 2-octanone and 2-alkanol = 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, and 2-octanol. The solvents used were n-hexane, toluene, methyl tert-butyl ether (MTBE), and supercritical carbon dioxide SCCO 2 (pressure P - 10.0 MPa). The temperature range was T - (288.15 to 308.27) K. Chiral analysis of the reaction products showed that the enzyme used in this study was stereoselective for the 2-octanone reaction system, i.e. only (S)-(+)-2-octanol was formed. For the reactions involving butanone, pentanone, and hexanone, the products were racemic mixtures of the respective (S)-(+)-2-alkanol and the (R)-(-)-2-alkanol. Chiral analysis showed that for the 2-heptanone reaction system, the 2-alkanol product was a mixture of (S)-(+)-2-heptanol and (R)-(-)-2-heptanol, at the respective mole fractions of 0.95 and 0.05. The equilibrium constant for the reaction system involving 2-butanone carried out in n-hexane was measured at several temperatures. For this reaction, the values for the thermodynamic reaction quantities at T= 298. 15 K are: K= 0.838±0.013; the standard molar Gibbs free energy change ΔrgHm° = (0.44±0.040) kJ · mol-1; the standard molar enthalpy change ΔrgHm° = -(1.2±1.7) kJ mol-1, and the standard molar entropy change ΔrgHm° = -(5.5±5.7) J K-1 mol-1. Interestingly, inspection of the values of the equilibrium constants for these reactions carried out in n-hexane, toluene, MTBE, and SCCO2 shows that these values are comparable and have little dependence on the solvent used to carry out the reaction. The values of the equilibrium constants decrease monotonically with increasing value of the number of carbons Nc and trend towards a limiting value of ≈0.30 for Nc > 8. Published by Elsevier Ltd.
- Tewari, Yadu B.,Schantz, Michele M.,Phinney, Karen W.,Rozzell, J. David
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- Microbial asymmetric CH oxidations of simple hydrocarbons: A novel monooxygenase activity of the topsoil microorganism Bacillus megaterium
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A Bacillus megaterium strain was isolated from topsoil by a selective screening procedure with allylbenzene as xenobiotic substrate. It is demonstrated for the first time, from analytical-scale experiments, that this microorganism hydroxylates a variety of simple n-alkanes (hexane through nonane) and cycloalkanes (cyclohexane and cyclooctane) to afford optically active alcohols in up to 99% enantiomeric excess (ee). In the case of the n-alkanes, the ω-1, ω-2 and ω-3 regioisomers were obtained. This enzymatic activity is unprecedented for Bacillus megaterium strains and is generally rarely observed in bacteria.
- Adam, Waldemar,Lukacs, Zoltan,Saha-Moeller, Chantu R.,Weckerle, Bernhard,Schreier, Peter
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p. 2923 - 2926
(2007/10/03)
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- Efficient Stereocontrolled Total Syntheses of Racemic and Natural Brefeldin-A
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Brefeldin-A, an antiobiotic fungal metabolite, has been obtained in both racemic and natural forms through a direct approach that employs norbornenone and 6-heptyn-2-ol as the basic starting materials.
- Drian, Claude Le,Greene, Andrew E.
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p. 5473 - 5483
(2007/10/02)
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