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Selective oxidation of minimally protected aminopolyols, using galactose oxidase variant F2, affords biologically relevant iminosugars.

Here, we report a chemoenzymatic approach for the preparation of a small panel of biologically important iminosugars from readily available aldoses. Our approach involves an in vitro transaminase-mediated amination of aldoses in combination with an in vivo selective oxidation of the chemically protected transaminase products, using Gluconobacter oxydans DSM 2003 whole cells. Chemically catalysed deprotection and reduction steps afford a selection of valuable iminocyclitols. Science Foundation Ireland Citation tool on publisher's site lists issue number as 11 but DOI and all other details indicate issue 13 is the correct citation.

Nature exploits biosynthetic cascades to construct numerous molecules from a limited set of starting materials. A deeper understanding of biosynthesis and extraordinary developments in gene technology has allowed the manipulation of natural pathways and construction of artificial cascades for the preparation of a range of molecules, which would be challenging to access using traditional synthetic chemical approaches. Alongside these metabolic engineering strategies, there has been continued interest in developing in vivo and in vitro biocatalytic cascades. Advancements in both metabolic engineering and biocatalysis are complementary, and this article aims to highlight some of the most exciting developments in these two areas with a particular focus on exploring those that have the potential to advance both pathway engineering and more traditional biocatalytic cascade development.

There is continued interest in developing cascade processes for the synthesis of key chiral building blocks and bioactive natural products (or analogues). Here, we report a hybrid bio-organocatalytic cascade for the synthesis of a small panel of 2-substituted piperidines, relying on a transaminase to generate a key reactive intermediate for the complexity building Mannich reaction.

The development of effective high-throughput screening assays has contributed greatly to the wealth of designer enzymes available, by enabling rapid identification of desired variants from large mutant libraries. Here, we report a general and operationally simple end-point assay for transaminases that enables the screening of both amine donors and acceptors in liquid phase. The spectrophotometric-based screen exploits the amine donor 2aminoethylaniline (2-AEA) and relies on reaction of in situ generated indole with Ehrlich’s reagent. The assay has also been adapted to allow screening in the reverse direction by addition of indole and subsequent spectrophotometric analysis. Importantly, the screen provides qualitative information on the enantio-preference of the individual biocatalysts. To increase the assay throughput, an engineered expression strain (E. coli BL21(DE3) ΔtnaA) lacking tryptophanase activity, was generated to enable reliable and direct evaluation of individual colonies arrayed on agar plates.

Background Transfer students are a growing population of undergraduate psychology majors who are academically at-risk but often underserved by 4-year institutions. Objective We describe a transfer learning community (TLC) for entering psychology transfer students and report its impact on participants social and academic integration and success. Method A mixed-method design was used to compare academic success metrics (archival measures of first-semester grade point average and probation rates) of participants with entering transfer majors not participating in the learning community. A participant survey was also created and used to measure student perceptions of the TLC, as well as perceived challenges of transferring during the Covid-19 pandemic and how the TLC helped to mitigate them. Results During its first year, the TLC served 72 entering transfer majors across two cohorts. Participants significantly out-performed non-participant psychology transfer majors on first-semester grade point average and were significantly less likely to be placed on academic probation after their first semester than non-participant transfer majors. Conclusion The widely-reported benefits of learning communities for first-year psychology students are adaptable to the more at-risk population of transfer students. Teaching Implications Technology-enabled teaching tools can be used to build virtual community in hybrid and synchronous online learning environments.

The conversion of readily available monosaccharides to high-value amino alcohols using a key biocatalytic step is an attractive strategy for the preparation of these chiral synthons. Here, we report a previously undescribed example of the direct amination of monosaccharides, which exist predominantly in their cyclic form at equilibrium, using amine transaminase biocatalysts, providing access to a panel of amino alcohols in moderate to high conversion and isolated yield. A recently developed high-throughput colorimetric screen, employing o-xylylenediamine, was initially used to identify amine transaminase enzymes displaying this activity towards cyclic sugars and reactions were successfully scaled-up using isopropylamine.

An ω‐transaminase triggered intramolecular aza‐Michael reaction has been employed for the preparation of cyclic β‐enaminones in good yield and excellent enantio‐ and diastereoselectivity, starting from easily accessible prochiral ketoynones and commercially available enzymes. The powerful thermodynamic driving force associated with the spontaneous aza‐Michael reaction effectively displaces the transaminase reaction equilibrium towards product formation, using only two equivalents of isopropylamine. To demonstrate the potential of this methodology, we have combined this biocatalytic aza‐Michael step with annulation chemistry, affording unique stereo‐defined fused alkaloid architectures.

The development of biocatalytic routes for the synthesis of chiral amines starting from achiral building blocks is highly desirable. Here, we report a self-sufficient whole-cell system for the conversion of a model ketone to the corresponding cyclic imine, in good isolated yield (42%) and excellent enantioselectivity (>99% ee). The Corynebacterium glutamicum host produces the transaminase biocatalyst, cofactor and ‘smart’ amine donor (cadaverine or putrescine) in vivo, and highlights the potential for producing high-value chemicals from readily available building blocks. The report represents the first example of the application of a metabolically engineered organism for the production of smart diamine donors and their application in a transaminase biotransformation.

An alcohol dehydrogenase‐mediated asymmetric reduction and subsequent intramolecular oxa‐Michael reaction has been developed for the preparation of tetrahydropyrans (or oxanes) and tetrahydrofurans, in excellent conversion, yield and high enantiomeric and diastereomeric excess. To highlight the utility of the methodology, we report the synthesis of an analogue of the fungal antioxidant brocaketone A. Also described is the preparation of the (‐)‐(R,R)‐enantiomer of the natural product, (+)‐(S,S)‐(cis‐6‐methyltetrahydropyran‐2‐yl)acetic acid.

The “smart” amine donors o‐xylylenediamine and cadaverine were employed for the rapid screening of a large ketone library and subsequent preparative‐scale synthesis of selected compounds using a commercially available amine transaminase, ATA256. The methodology enables both screening and preparative‐scale biotransformations to be performed with a single enzyme and simplifies the generation of sp3‐rich small‐molecule libraries.

Significant advancements in protein engineering and DNA technology have seen biocatalytic transformations take the place of traditional chemical manipulations in both academia and industry for the preparation of active pharmaceutical ingredients (APIs) and other medicinally relevant compounds. However, despite the large repertoire of commercially available biocatalysts that are readily accessible, enzymes which mediate the formation of C–C bonds and those that enable convergent synthesis remain largely undeveloped. To expand the scope of biocatalytic retrosynthesis and enable it to complement traditional chemical retrosynthesis it is essential to develop a ‘toolbox’ of biocatalysts which build molecular complexity. Of particular interest is the development of one-pot enzymatic cascades for the synthesis of functionalised, chiral building blocks without the need for protecting group manipulations or harsh reaction conditions. Highly regio- and stereoselective chemoenzymatic cascades have been developed for the synthesis of a range of chiral amines employing ω-transaminases and monoamine oxidase variants.

A method to efficiently immobilize enzymes on 3D printed continuous- fl ow devices is presented. Application of these chemically modi fi ed devices enables rapid screening of immobilization mechanisms and reaction conditions, simple transfer of optimised conditions into tailored printed micro fl uidic reactors and development of continuous- fl ow biocatalytic processes. The bioreactors showed good activity (8 – 20.5 μ mol h − 1 mg enz − 1 ) in the kinetic resolution of 1-methylbenzylamine, and very good stability ( ca. 100 h under fl ow).

Amine transaminases are important biocatalysts for the synthesis of chiral primary amines. Unlike many enzymes that have been employed for the synthesis of optically active amines, amine transaminases are capable of asymmetric synthesis and do not rely on costly cofactors that must be regenerated in situ. However, their application as general catalysts for the preparation of amines is hampered by a limited substrate scope, substrate and (co)product inhibition and difficulties associated with displacing challenging reaction equilibrium. There has been important progress made to overcome these challenges, including the development of enzymes with broader substrate scope and the design of methodology to effectively displace the reaction equilibrium. Amine transaminases are also being applied in an increasing range of (chemo)enzymatic cascades and immobilized for applications in flow.

[21294-14-4] C8H14N2Cl2 (MW 209.12) InChI = S/C8H12N2.2ClH/c9-5-7-3-1-2-4-8(7)6-10;;/h1-4H,5-6,9-10H2;2*1H InChIKey = VDEOIFDDSWXYDA-UHFFFAOYSA-N (reagent used as an amine donor for the biocatalytic synthesis of chiral primary amines) Alternate Names: α,α′-diamino-o-xylene dihydrochloride, 1,2-bis(aminomethyl)benzene dihydrochloride, ortho-phenylene-bis(methylamine) dihydrochloride. Physical Data: mp 161–167 °C. Solubility: soluble in water, methanol, and DMSO. Insoluble in DCM, ethyl acetate, and diethyl ether. Form Supplied in: white crystalline solid. Available from commercial suppliers including Sigma-Aldrich. Analysis of Reagent Purity: contains ∼4% water as purchased from commercial suppliers. Method of analysis is not described. Handling and Storage: recommended storage temperature is 2–8 °C. The reagent is stable under these storage conditions. There are no special handling requirements associated with the use of this reagent.

The widespread application of ω‐transaminases as biocatalysts for chiral amine synthesis has been hampered by fundamental challenges, including unfavorable equilibrium positions and product inhibition. Herein, an efficient process that allows reactions to proceed in high conversion in the absence of by‐product removal using only one equivalent of a diamine donor (ortho‐xylylenediamine) is reported. This operationally simple method is compatible with the most widely used (R)‐ and (S)‐selective ω‐TAs and is particularly suitable for the conversion of substrates with unfavorable equilibrium positions (e.g., 1‐indanone). Significantly, spontaneous polymerization of the isoindole by‐product generates colored derivatives, providing a high‐throughput screening platform to identify desired ω‐TA activity.

Herein we report a one-pot protocol for the deracemisation of chiral benzylic amines employing a novel monoamine oxidase–ω-transaminase cascade, allowing access to enantiopure compounds in >99 % ee. We also demonstrate that the same enzymatic cascade can be employed for the dealkylation of secondary amines with >99 % conversion.

Biocatalytic approaches to the synthesis of optically pure chiral amines, starting from simple achiral building blocks, are highly desirable because such motifs are present in a wide variety of important natural products and pharmaceutical compounds. Herein, a novel one-pot ω-transaminase (TA)/monoamine oxidase (MAO-N) cascade process for the synthesis of chiral 2,5-disubstituted pyrrolidines is reported. The reactions proceeded with excellent enantio- and diastereoselectivity (>94 % ee; >98 % de) and can be performed on a preparative scale. This methodology exploits the complementary regio- and stereoselectivity displayed by both enzymes, which ensures that the stereogenic center established by the transaminase is not affected by the monoamine oxidase, and highlights the potential of this multienzyme cascade for the efficient synthesis of chiral building blocks. Mirror mirror on the wall: A ω-transaminase (ω-TA)/monoamine oxidase (MAO-N) cascade process for the asymmetric synthesis of chiral 2,5-disubstituted pyrrolidines is reported. The methodology exploits the complementary regio- and stereoselectivity displayed by both enzymes, which ensures that the stereogenic center established by the TA reaction is not affected by the MAO-N catalyzed step. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The expanding “toolbox” of biocatalysts opens new opportunities to redesign synthetic strategies to target molecules by incorporating a key enzymatic step into the synthesis. Herein, we describe a general biocatalytic approach for the enantioselective preparation of 2,6-disubstituted piperidines starting from easily accessible pro-chiral ketoenones. The strategy represents a new biocatalytic disconnection, which relies on an ω-TA-mediated aza-Michael reaction. Significantly, we show that the reversible enzymatic process can power the shuttling of amine functionality across a molecular framework, providing access to the desired aza-Michael products.

The application of ω-transaminase biocatalysts for the synthesis of optically pure chiral amines presents a number of challenges, including difficulties associated with displacing the challenging reaction equilibria. Herein, we report a highly effective approach using low equivalents of the novel diamine donor, cadaverine, which enables high conversions of challenging substrates to the corresponding chiral amines in excellent ee. This approach paves the way for the design of self-sufficient fermentation processes combining transaminase biotransformations with existing strategies for cadaverine production via decarboxylation of endogenous lysine.

The ability of Rhodococcus rhodochrous (NCIMB 9703) to catalyse the regio- and stereoselective hydroxylation of a range of benzyloxy-substituted heterocycles has been investigated. Incubation of 2-benzyloxytetrahydropyrans with resting cell suspensions of the organism yielded predominantly a mixture of 5-hydroxylated isomers in combined yields of up to 40%. Exposure of the corresponding 2-benzyloxytetrahydrofuran derivatives to the cell suspensions gave predominantly the 4-hydroxylated isomers in yields of up to 26%. Most interestingly, 2-(4-nitrobenzyloxy)tetrahydrofuran and 2-(4-nitrobenzyloxy)tetrahydropyran were transformed in high yields to the 4-hydroxylated and 5-hydroxylated products, respectively.

A high-throughput screening protocol for evaluating chimeric, self-sufficient P450 biocatalysts and their mutants against a panel of substrates was developed, leading to the identification of a number of novel biooxidation activities.

An atom-efficient and stereoselective synthesis has been developed for the preparation of a-2H-labelled(S)-a-amino acids, starting from a novel chiral diketopiperazine scaffold. Efficient mono-alkylation of the chiral template afforded the (S)-substituted adducts with the nature of the electrophile significantly effecting the stereochemical outcome. Subsequent alkylation was totally selective producing the 1,4-cis adduct as the sole diastereoisomer. The deprotection was carried out using cerium ammonium nitrate followed by acid hydrolysis affording the enantipure a-amino acids. Higher Education Authority Irish Research Council for Science, Engineering and Technology

The chemoselective reductive cyclization of diones of type (I) in the presence of transaminase ATA113 is presented.

A simple and efficient one-step procedure is described for the synthesis of a number of symmetrical 1,4-disubstituted piperazine-2,5-diones under phase transfer conditions. The reactions are carried out at room temperature, starting from a suitable N-chloroacetamide in the presence of an aqueous solution of sodium hydroxide. Piperazine-2,5-diones were obtained with excellent selectivity in yields of up to 90%. Higher Education Authority Irish Research Council for Science, Engineering and Technology

Conformationally restricted amino acids are important components in peptidomimetics and drug design. Herein, we describe the synthesis of a novel, non-proteinogenic constrained delta amino acid containing a cyclobutane ring, cis-3(aminomethyl)cyclobutane carboxylic acid (ACCA). The synthesis of the target amino acid was achieved in seven steps, with the key reaction being a base induced intramolecular nucleophilic substitution. A small library of dipeptides was prepared through the coupling of ACCA with proteinogenic amino acids. Author has checked copyright AMS. The delta sign is in the article title rather that the word delta. Not sure where to find this.

Cytochrome P450 monooxygenases (P450s or CYPs) are a unique family of enzymes which are capable of catalysing the regio- and stereospecific oxidation of non-functionalised hydrocarbons. Despite the enormous synthetic potential of P450s, these enzymes have yet to be extensively employed for research purposes or in industry. Lack of stability, low activity, narrow substrate specificity, expensive cofactor requirements, limited solvent tolerance and electron supply are some of the main reasons why the academic and industrial implementation of these important biocatalysts remains a challenge. Considering the significance of P450s, many research groups have focused on improving their properties in an effort to make more robust catalysts with broad synthetic applications. This article focuses on some of the factors that have limited the exploitation of P450s and explores some of the significant steps that have been taken towards addressing these limitations.

In order to increase our understanding of diabetes-related muscle weakness, we carried out a mass spectrometry-based proteomic analysis of skeletal muscle preparations from the Goto-Kakizaki rat model of type-2 diabetes. Fluorescence difference in-gel electrophoresis was performed to determine potential differences in the global protein expression profile of muscle extracts. Besides changes in contractile proteins and metabolic enzymes, the abundance of the small stress proteins αB-crystallin and Hsp27 was significantly increased. The up-regulation of the low-molecular-mass heat shock protein Hsp27 was confirmed by an alternative fluorescent staining method of two-dimensional gels and immunoblotting. The observed protein alterations in the cellular stress response, distinct metabolic pathways, regulatory mechanisms and the contractile apparatus might be directly or indirectly associated with peripheral resistance to insulin signalling, making these newly identified muscle proteins potential biomarkers of type-2 diabetes. Increased levels of molecular chaperones suggest considerably enhanced cellular stress levels in diabetic muscle fibres.

An efficient one-pot synthesis is described for the preparation of 1,4-disubstituted piperazine-2,5-diones starting from a suitable amine and chloroacetyl chloride in the presence of an aqueous base. The resulting chloroacetamide is cyclised in situ by employing the phase-transfer (PT) catalyst, benzyltriethylammonium chloride (TEBA). The products are isolated in excellent yields of up to 90%.

An atom-efficient and stereoselective synthesis has been developed for the preparation of alpha-2H-labelled (S)-alpha-amino acids, starting from a novel chiral diketopiperazine scaffold. Efficient mono-alkylation of the chiral template afforded the (S)-substituted adducts with the nature of the electrophile significantly effecting the stereochemical outcome. Subsequent alkylation was totally selective producing the 1,4-cis adduct as the sole diastereoisomer. The deprotection was carried out using cerium ammonium nitrate followed by acid hydrolysis affording the enantipure alpha-amino acids.

A simple and efficient one-step procedure is described for the synthesis of a number of symmetrical 1,4-disubstituted piperazine-2,5-diones under phase transfer conditions. The reactions are carried out at room temperature, starting from a suitable N-chloroacetamide in the presence of an aqueous solution of sodium hydroxide. Piperazine-2,5-diones were obtained with excellent selectivity in yields of up to 90%.

An efficient one-pot synthesis is described for the preparation of 1,4-disubstituted piperazine-2,5-diones starting from a suitable amine and chloroacetyl chloride in the presence of an aqueous base. The resulting chloroacetamide is cyclised in situ by employing the phase-transfer (PT) catalyst, benzyltriethylammonium chloride (TEBA). The products are isolated in excellent yields of up to 90%. Higher Education Authority Irish Research Council for Science, Engineering and Technology

Cytochrome P450 RhF displays a high degree of substrate promiscuity, mediating a range of O-dealkylations, aromatic hydroxylations, epoxidations and asymmetric sulfoxidations. The self-sufficient nature of this CYP coupled with its ability to catalyse the oxidation of a wide range of functional groups highlights this enzyme as an excellent starting template for directed evolution and promising alternate to P450 BM3.