5524-05-0Relevant articles and documents
Novel reductase participation in the syn-addition of hydrogen to the C=C bond of enones in the cultured cells of Nicotiana tabacum
Shimoda, Kei,Ito, Diana I.,Izumi, Shunsuke,Hirata, Toshifumi
, p. 355 - 358 (1996)
A reductase isolated from cultured cells of Nicotiana tabacum has been characterized and used in the reduction of a C=C bond adjacent to a carbonyl group. The stereochemistry of the latter reaction has been investigated by 2H NMR and mass spectroscopy. It was found that the reductase reduces stereospecifically the C=C bond of verbenone and carvone by syn addition of hydrogen from the re face at the β-position and the re face at the α-position to the carbonyl group; the hydrogen atoms participating in the enzymatic reduction at the α- and β-positions originate from the medium (H2O) and the pro-4S hydrogen of NADPH, respectively.
STEREOCHEMISTRY OF REDUCTION OF THE ENDOCYCLIC DOUBLE BOND OF (-)-CARVONE WITH THE ENZYME PREPARATION FROM CULTURED CELLS OF NICOTIANA TABACUM
Hirata, Toshifumi,Tang, Yixiong,Okano, Kuniko,Suga, Takayuki
, p. 3331 - 3334 (1989)
The stereochemistry of the reduction of the endocyclic C-C double bond of (4R)-(-)-carvone with an enzyme preparation from cultured cells of Nicotiana tabacum was investigated by (2)H NMR and mass spectroscopy.It was found that: (i) the enzyme preparation regioselectively reduces only the endocyclic double bound; (ii) the reduction occurs stereospecifically by anti addition of hydrogen from the si face at C-1 and the re face at C-6 of carvone, resulting in the formation of (1R,4R)-(+)-dihydrocarvone; (iii) the hydrogen atoms participating in the enzymatic reduction at C-1 and C-6 originate from the medium and the pro-4R hydrogen of NADH, respectively.Key Word Index - Nicotiana tabacum; Solanaceae; cultured cells; enzymatic reduction; stereochemistry; carvone.
Asymmetric Reduction of (R)-Carvone through a Thermostable and Organic-Solvent-Tolerant Ene-Reductase
Tischler, Dirk,G?dke, Eric,Eggerichs, Daniel,Gomez Baraibar, Alvaro,Mügge, Carolin,Scholtissek, Anika,Paul, Caroline E.
, p. 1217 - 1225 (2020)
Ene-reductases allow regio- and stereoselective reduction of activated C=C double bonds at the expense of nicotinamide adenine dinucleotide cofactors [NAD(P)H]. Biological NAD(P)H can be replaced by synthetic mimics to facilitate enzyme screening and process optimization. The ene-reductase FOYE-1, originating from an acidophilic iron oxidizer, has been described as a promising candidate and is now being explored for applied biocatalysis. Biological and synthetic nicotinamide cofactors were evaluated to fuel FOYE-1 to produce valuable compounds. A maximum activity of (319.7±3.2) U mg?1 with NADPH or of (206.7±3.4) U mg?1 with 1-benzyl-1,4-dihydronicotinamide (BNAH) for the reduction of N-methylmaleimide was observed at 30 °C. Notably, BNAH was found to be a promising reductant but exhibits poor solubility in water. Different organic solvents were therefore assayed: FOYE-1 showed excellent performance in most systems with up to 20 vol% solvent and at temperatures up to 40 °C. Purification and application strategies were evaluated on a small scale to optimize the process. Finally, a 200 mL biotransformation of 750 mg (R)-carvone afforded 495 mg of (2R,5R)-dihydrocarvone (>95 % ee), demonstrating the simplicity of handling and application of FOYE-1.
Loop Swapping as a Potent Approach to Increase Ene Reductase Activity with Nicotinamide Adenine Dinucleotide (NADH)
M?hler, Christoph,Kratzl, Franziska,Vogel, Melina,Vinnenberg, Stefan,Weuster-Botz, Dirk,Castiglione, Kathrin
, p. 2505 - 2513 (2019)
The asymmetric reduction of alkenes is a widely used transformation in industry. Ene reductases (ERs) are (βα)8-barrel folded enzymes capable of catalyzing this hydrogenation reaction. At the expense of nicotinamide coenzymes, ERs can reduce a wide range of electron-deficient alkenes in an anti-specific manner and with high regio- and stereoselectivities. However, a cost-effective industrial use of these enzymes is hampered, since most ERs prefer nicotinamide adenine dinucleotide phosphate (NADPH) to the more stable and less expensive non-phosphorylated nicotinamide adenine dinucleotide (NADH) as coenzyme. Here, we demonstrate an approach to both modify the biocatalysts coenzyme selectivity and strongly increase the activity and affinity with NADH. By swapping loop regions of the cyanobacterial NostocER1 for the corresponding regions of two NADH-favoring ERs, a strong alteration of the biocatalyst's coenzyme binding was achieved. This made possible a transfer of the respective donor-ER kinetic parameters to NostocER1. Additionally, outperformance of both donors in terms of activity was achieved through combinatorial swapping of loops of both species. These findings demonstrate the high potential of loop swapping as protein engineering approach to selectively optimize the coenzyme binding of ERs. (Figure presented.).
Investigating the Structure-Reactivity Relationships Between Nicotinamide Coenzyme Biomimetics and Pentaerythritol Tetranitrate Reductase
Tan, Zhuotao,Han, Yaoying,Fu, Yaping,Zhang, Xiaowang,Xu, Mengjiao,Na, Qi,Zhuang, Wei,Qu, Xudong,Ying, Hanjie,Zhu, Chenjie
, p. 103 - 113 (2021/10/07)
Ene reductases (ERs) are attractive biocatalysts in terms of their high enantioselectivity and expanded substrate scope. Recent works have proved that synthetic nicotinamide coenzyme biomimetics (NCBs) can be used as easily accessible alternatives to natural cofactors in ER-catalyzed reactions. However, the structure-reactivity relationships between NCBs and ERs and influence factors are still poorly understood. In this study, a series of C-5 methyl modified NCBs were synthesized and tested in the PETNR-catalyzed asymmetric reductions. The physicochemical properties of these NCBs including electrochemical properties, stability, and kinetic behavior were studied in detail. The results showed that hydrophobic interaction caused by the introduced methyl group contributed to the stabilization of binding conformation in enzyme active site, resulting in comparable catalytic activity with that of NADPH. Molecular dynamics and steered molecular dynamics simulations were further performed to explain the binding mechanism between PETNR and NCBs, which revealed that stable catalytic conformation, appropriate donor-acceptor distance and angle, as well as free dissociation energy are important factors affecting the activity of NCBs. (Figure presented.).
A robust and stereocomplementary panel of ene-reductase variants for gram-scale asymmetric hydrogenation
Nett, Nathalie,Duewel, Sabine,Schmermund, Luca,Benary, Gerrit E.,Ranaghan, Kara,Mulholland, Adrian,Opperman, Diederik J.,Hoebenreich, Sabrina
, (2021/01/25)
We report an engineered panel of ene-reductases (ERs) from Thermus scotoductus SA-01 (TsER) that combines control over facial selectivity in the reduction of electron deficient C[dbnd]C double bonds with thermostability (up to 70 °C), organic solvent tolerance (up to 40 % v/v) and a broad substrate scope (23 compounds, three new to literature). Substrate acceptance and facial selectivity of 3-methylcyclohexenone was rationalized by crystallisation of TsER C25D/I67T and in silico docking. The TsER variant panel shows excellent enantiomeric excess (ee) and yields during bi-phasic preparative scale synthesis, with isolated yield of up to 93 % for 2R,5S-dihydrocarvone (3.6 g). Turnover frequencies (TOF) of approximately 40 000 h?1 were achieved, which are comparable to rates in hetero- and homogeneous metal catalysed hydrogenations. Preliminary batch reactions also demonstrated the reusability of the reaction system by consecutively removing the organic phase (n-pentane) for product removal and replacing with fresh substrate. Four consecutive batches yielded ca. 27 g L?1 R-levodione from a 45 mL aqueous reaction, containing less than 17 mg (10 μM) enzyme and the reaction only stopping because of acidification. The TsER variant panel provides a robust, highly active and stereocomplementary base for further exploitation as a tool in preparative organic synthesis.
Total Synthesis of (?)-Rotundone and (?)-epi-Rotundone from Monoterpene Precursors
Rüthi, Fabian,Schr?der, Fridtjof
, (2020/10/30)
The first total synthesis of (?)-rotundone has been accomplished from (+)-(R)-limonene and therefore for the first time from an unrelated monoterpene instead of modifying structurally closely related sesquiterpene precursors such as α-guaiene. Challenges such as intermediates with stereocenters prone to epimerization by enolization were overcome by designing a β-methyl-keto route starting from (+)-(R)-limonene which finally gave (?)-rotundone by Nazarov cyclization of a precursor 13a. Diastereomer (?)-epi-rotundone was separated from (?)-rotundone chromatographically. An alternative route from rac-citronellal provided a diastereomer mixture of racemic Nazarov precursor 13 through a TRIP-catalyzed intramolecular aldolization, thus indicating that the Nazarov cyclization precursor 13a is in principle accessible from (?)-(S)-citronellal. The 11-step synthesis from (+)-(R)-limonene with ca. 1 % overall yield confirmed the absolute configuration of (?)-rotundone and provided samples of good olfactory quality.
Photocontrolled Cobalt Catalysis for Selective Hydroboration of α,β-Unsaturated Ketones
Beltran, Frédéric,Bergamaschi, Enrico,Funes-Ardoiz, Ignacio,Teskey, Christopher J.
supporting information, p. 21176 - 21182 (2020/09/17)
Selectivity between 1,2 and 1,4 addition of a nucleophile to an α,β-unsaturated carbonyl compound has classically been modified by the addition of stoichiometric additives to the substrate or reagent to increase their “hard” or “soft” character. Here, we demonstrate a conceptually distinct approach that instead relies on controlling the coordination sphere of a catalyst with visible light. In this way, we bias the reaction down two divergent pathways, giving contrasting products in the catalytic hydroboration of α,β-unsaturated ketones. This includes direct access to previously elusive cyclic enolborates, via 1,4-selective hydroboration, providing a straightforward and stereoselective route to rare syn-aldol products in one-pot. DFT calculations and mechanistic experiments confirm two different mechanisms are operative, underpinning this unusual photocontrolled selectivity switch.
C3 and C6 Modification-Specific OYE Biotransformations of Synthetic Carvones and Sequential BVMO Chemoenzymatic Synthesis of Chiral Caprolactones
Issa, Issa S.,Toogood, Helen S.,Johannissen, Linus O.,Raftery, James,Scrutton, Nigel S.,Gardiner, John M.
supporting information, p. 2983 - 2988 (2019/01/24)
The scope for biocatalytic modification of non-native carvone derivatives for speciality intermediates has hitherto been limited. Additionally, caprolactones are important feedstocks with diverse applications in the polymer industry and new non-native terpenone-derived biocatalytic caprolactone syntheses are thus of potential value for industrial biocatalytic materials applications. Biocatalytic reduction of synthetic analogues of R-(?)-carvone with additional substituents at C3 or C6, or both C3 and C6, using three types of OYEs (OYE2, PETNR and OYE3) shows significant impact of both regio-substitution and the substrate diastereomer. Bioreduction of (?)-carvone derivatives substituted with a Me and/or OH group at C6 is highly dependent on the diastereomer of the substrate. Derivatives bearing C6 substituents larger than methyl moieties are not substrates. Computer docking studies of PETNR with both (6S)-Me and (6R)-Me substituted (?)-carvone provides a model consistent with the outcomes of bioconversion. The products of bioreduction were efficiently biotransformed by the Baeyer–Villiger monooxygenase (BVase) CHMO_Phi1 to afford novel trisubstituted lactones with complete regioselectivity to provide a new biocatalytic entry to these chiral caprolactones. This provides both new non-native polymerization feedstock chemicals, but also with enhanced efficiency and selectivity over native (+)-dihydrocarvone Baeyer–Villigerase expansion. Optimum enzymatic reactions were scaled up to 60–100 mg, demonstrating the utility for preparative biocatalytic synthesis of both new synthetic scaffold-modified dihydrocarvones and efficient biocatalytic entry to new chiral caprolactones, which are potential single-isomer chiral polymer feedstocks.
Asymmetric whole-cell bio-reductions of (R)-carvone using optimized ene reductases
M?hler, Christoph,Burger, Christian,Kratzl, Franziska,Weuster-Botz, Dirk,Castiglione, Kathrin
, (2019/07/18)
(2R,5R)-dihydrocarvone is an industrially applied building block that can be synthesized by site-selective and stereo-selective C=C bond bio-reduction of (R)-carvone. Escherichia coli (E. coli) cells overexpressing an ene reductase from Nostoc sp. PCC7120 (NostocER1) in combination with a cosubstrate regeneration system proved to be very effective biocatalysts for this reaction. However, the industrial applicability of biocatalysts is strongly linked to the catalysts’ activity. Since the cell-internal NADH concentrations are around 20-fold higher than the NADPH concentrations, we produced E. coli cells where the NADPH-preferring NostocER1 was exchanged with three different NADH-accepting NostocER1 mutants. These E. coli whole-cell biocatalysts were used in batch operated stirred-tank reactors on a 0.7 l-scale for the reduction of 300 mM (R)-carvone. 287 mM (2R,5R)-dihydrocarvone were formed within 5 h with a diasteromeric excess of 95.4% and a yield of 95.6%. Thus, the whole-cell biocatalysts were strongly improved by using NADH-accepting enzymes, resulting in an up to 2.1-fold increased initial product formation rate leading to a 1.8-fold increased space-time yield when compared to literature.
