- A High-Throughput Screening Method for the Directed Evolution of Hydroxynitrile Lyase towards Cyanohydrin Synthesis
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Chiral cyanohydrins are useful intermediates in the pharmaceutical and agricultural industries. In nature, hydroxynitrile lyases (HNLs) are a kind of elegant tool for enantioselective hydrocyanation of carbonyl compounds. However, currently available methods for demonstrating hydrocyanation are still stalled at precise, but low-throughput, GC or HPLC analyses. Herein, we report a chromogenic high-throughput screening (HTS) method that is feasible for the cyanohydrin synthesis reaction. This method was highly anti-interference and sensitive, and could be used to directly profile the substrate scope of HNLs either in cell-free extract or fermentation clear broth. This HTS method was also validated by generating new variants of PcHNL5 that presented higher catalytic efficiency and stronger acidic tolerance in variant libraries.
- Zheng, Yu-Cong,Ding, Liang-Yi,Jia, Qiao,Lin, Zuming,Hong, Ran,Yu, Hui-Lei,Xu, Jian-He
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- Structure-Guided Tuning of a Hydroxynitrile Lyase to Accept Rigid Pharmaco Aldehydes
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The chiral vicinal C-O/C-N bifunctional groups generated from enzymatic hydrocyanation represents a useful methodology. However, construction of the pharmacophore of β2-adrenoreceptor agonists with this method remains a great challenge because of complete racemization of the benzylic alcohol during deprotection of the acetal groups. In this study, structure-guided redesign of a hydroxynitrile lyase originating from Prunus communis (PcHNL5) enables a highly enantioselective hydrocyanation of rigid benzo-ketal aldehyde which was proved to be resistant against racemization during the deprotection step, with dramatically improved productivity (>95% conversion vs 2-adrenoreceptor agonist, in an optically pure form (>99% ee) with an overall yield of 54%, which is the highest value reported.
- Hong, Ran,Li, Fu-Long,Lin, Guo-Qiang,Lin, Zuming,Xu, Jian-He,Yu, Hui-Lei,Zheng, Yu-Cong
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p. 5757 - 5763
(2020/06/09)
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- Immobilized Baliospermum montanum hydroxynitrile lyase catalyzed synthesis of chiral cyanohydrins
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Hydroxynitrile lyase (HNL) catalyzed enantioselective C–C bond formation is an efficient approach to synthesize chiral cyanohydrins which are important building blocks in the synthesis of a number of fine chemicals, agrochemicals and pharmaceuticals. Immobilization of HNL is known to provide robustness, reusability and in some cases also enhances activity and selectivity. We optimized the preparation of immobilization of Baliospermium montanum HNL (BmHNL) by cross linking enzyme aggregate (CLEA) method and characterized it by SEM. Optimization of biocatalytic parameters was performed to obtain highest % conversion and ee of (S)-mandelonitrile from benzaldehyde using CLEA-BmHNL. The optimized reaction parameters were: 20 min of reaction time, 7 U of CLEA-BmHNL, 1.2 mM substrate, and 300 mM citrate buffer pH 4.2, that synthesized (S)-mandelonitrile in ~99% ee and ~60% conversion. Addition of organic solvent in CLEA-BmHNL biocatalysis did not improve in % ee or conversion of product unlike other CLEA-HNLs. CLEA-BmHNL could be successfully reused for eight consecutive cycles without loss of conversion or product formation and five cycles with a little loss in enantioselectivity. Eleven different chiral cyanohydrins were synthesized under optimal biocatalytic conditions in up to 99% ee and 59% conversion, however the % conversion and ee varied for different products. CLEA-BmHNL has improved the enantioselectivity of (S)-mandelonitrile synthesis compared to the use of purified BmHNL. Nine aldehydes not tested earlier with BmHNL were converted into their corresponding (S)-cyanohydrins for the first time using CLEA-BmHNL. Among the eleven (S)-cyanohydrins syntheses reported here, eight of them have not been synthesized by any CLEA-HNL. Overall, this study showed preparation, characterization of a stable, robust and recyclable biocatalyst i.e. CLEA-BmHNL and its biocatalytic application in the synthesis of different (S)-aromatic cyanohydrins.
- Jangir, Nisha,Padhi, Santosh Kumar
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- An R-selective hydroxynitrile lyase from Arabidopsis thaliana with an α/β-hydrolase fold
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Folding and selectivity: The noncyanogenic plant Arabidopsis thaliana contains a new hydroxynitrile lyase, which was cloned and characterized. This enzyme is readily available form a recombinant source, has a broad range of substrates, and enantioselectively transforms aliphatic and aromatic aldehydes as well as ketones into the corresponding R-cyanohydrins. (Chemical Equation Presented).
- Andexer, Jennifer,Von Langermann, Jan,Mell, Annett,Bocola, Marco,Kragl, Udo,Eggert, Thorsten,Pohl, Martina
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p. 8679 - 8681
(2008/09/18)
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- Synthesis of aromatic 1,2-amino alcohols utilizing a bienzymatic dynamic kinetic asymmetric transformation
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The applicability of the recent published bienzymatic protocol for the synthesis of (R)-2-amino-1-phenylethanol was tested using L-threonine aldolase from Pseudomonas putida and L-tyrosine decarboxylase from either Enterococcus faecalis (Efa) or two genes from Enterococcus faecium (Efil, Efi2). In all 21 benzaldehyde derivatives were applied for an initial TLC screening. On a small scale, octopamine and noradrenaline were obtained as (S)-enantiomers using Efil. Three protocols were upscaled yielding enantioenriched (S)-octopamine (yield 99%, ee 81%), (R)-2-amino-1-phenylethanol (yield 61%, ee 62%) and (S)-noradrenaline (yield 76%, ee 79%).
- Steinreiber, Johannes,Schuermann, Martin,Van Assema, Friso,Wolberg, Michael,Fesko, Kateryna,Reisinger, Christoph,Mink, Daniel,Griengl, Herfried
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p. 1379 - 1386
(2008/04/03)
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- Process for preparing optically active cyanohydrins and secondary products
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The present invention relates to a process for preparing optically active cyanohydrins of the formula (II), by reacting an aldehyde of the formula (I) with HCN in a water-immiscible organic solvent in the presence of water, in the absence or presence of a buffer, in the presence of a (R)-hydroxynitrile lyase, where X, Y and Z in formula (II) have the same meaning as in formula (I), independently of each other are identical or different and are H, F, Cl, Br, I, OH, O(C1-C4-alkyl), OCOCH3, NHCOCH3, NO2 or C1-C4-alkyl.
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- Difficult substrates in the R-hydroxynitrile lyase catalyzed hydrocyanation reaction: Application of the mass transfer limitation principle in a two-phase system
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The application of a number of new and/or difficult substrates in the catalyzed hydrocyanation reaction by R-hydroxynitrile lyase from almonds is described. By using an aqueous-organic two-phase system and increasing the rate of the enzymatic reaction relative to the mass transfer rate, the enantiomeric purity was improved. By fine tuning the reaction parameters (temperature, pH, and the amount of enzyme) the hydrocyanation reaction was optimized for all substrates. The general principles described here can also be applied to optimize the reaction conditions for other substrates.
- Gerrits, Pieter J.,Marcus, Jan,Birikaki, Lemonia,Van der Gen, Arne
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p. 971 - 974
(2007/10/03)
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- Novel (R)-oxynitrilase sources for the synthesis of (R)-cyanohydrins in diisopropyl ether
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Apple, apricot, cherry and plum meal were prepared from the seeds or kernels of mature garden fruits. The preparations as well as almond meal were used as the source of (R)-oxynitrilase for the synthesis of aliphatic and aromatic cyanohydrins in diisoprop
- Kiljunen, Eero,Kanerva, Liisa T.
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p. 1225 - 1234
(2007/10/03)
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- (R)- and (S)-cyanohydrins using oxynitrilases in whole cells
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Almond meal and Sorghum bicolor shoots were used as the sources of oxynitrilases for the preparation of a number (R)- and (S)-arylcyanohydrins, respectively, from the corresponding aldehydes in diisopropyl ether. Two different in situ methods were used to introduce hydrogen cyanide into the reaction mixture. In method 1, acetone cyanohydrin decomposes enzymatically and/or chemically to hydrogen cyanide. In method 2, hydrogen cyanide freely evaporates from a solution in diisopropyl ether from one compartment of the reaction vessel and ends up to the other where it dissolves into the reaction mixture.
- Kiljunen, Eero,Kanerva, Liisa T.
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p. 1105 - 1116
(2007/10/03)
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