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Solarczek J, Kaspar F, Bauer P, Schallmey A. G-type Halohydrin Dehalogenases Catalyze Ring Opening Reactions of Cyclic Epoxides with Diverse Anionic Nucleophiles. Chemistry 2022; 28:e202202343. [PMID: 36214160 PMCID: PMC10099379 DOI: 10.1002/chem.202202343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Indexed: 11/07/2022]
Abstract
Halohydrin dehalogenases are promiscuous biocatalysts, which enable asymmetric ring opening reactions of epoxides with various anionic nucleophiles. However, despite the increasing interest in such asymmetric transformations, the substrate scope of G-type halohydrin dehalogenases toward cyclic epoxides has remained largely unexplored, even though this subfamily is the only one known to display activity with these sterically demanding substrates. Herein, we report on the exploration of the substrate scope of the two G-type halohydrin dehalogenases HheG and HheG2 and a newly identified, more thermostable member of the family, HheG3, with a variety of sterically demanding cyclic epoxides and anionic nucleophiles. This work shows that, in addition to azide and cyanide, these enzymes facilitate ring-opening reactions with cyanate, thiocyanate, formate, and nitrite, significantly expanding the known repertoire of accessible transformations.
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Hamajima S, Komura N, Tanaka HN, Imamura A, Ishida H, Ichiyanagi T, Ando H. Investigation of the Protection of the C4 Hydroxyl Group in Macrobicyclic Kdo Donors. MOLECULES (BASEL, SWITZERLAND) 2022; 28:molecules28010102. [PMID: 36615297 PMCID: PMC9822203 DOI: 10.3390/molecules28010102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022]
Abstract
Chemical synthesis of 3-deoxy-d-manno-2-octulosonic acid (Kdo)-containing glycans, such as bacterial lipopolysaccharides (LPSs) and capsular polysaccharides (CPSs), is in high demand for the development of vaccines against pathogenic bacteria. We have recently achieved the complete α-stereoselective glycosidation of Kdo using a macrobicyclic donor tethered at the C1 and C5 positions. In this study, to expand the scope of Kdo glycosidation, we sought to protect the 4-OH group, thereby shortening the reaction time and ensuring the conversion of the glycosyl acceptor via its selective removal. The protection of the 4-OH group influenced the reactivity of the Kdo donor, and the triisopropylsilyl (TIPS) group acted as a selectively removable booster. The 4-O-TIPS donor allowed the synthesis of the α(2,4)-linked dimeric Kdo sequence, which is widely found in bacterial LPSs.
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Rajakumara E, Saniya D, Bajaj P, Rajeshwari R, Giri J, Davari MD. Hijacking Chemical Reactions of P450 Enzymes for Altered Chemical Reactions and Asymmetric Synthesis. Int J Mol Sci 2022; 24:ijms24010214. [PMID: 36613657 PMCID: PMC9820634 DOI: 10.3390/ijms24010214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 12/09/2022] [Accepted: 12/12/2022] [Indexed: 12/25/2022] Open
Abstract
Cytochrome P450s are heme-containing enzymes capable of the oxidative transformation of a wide range of organic substrates. A protein scaffold that coordinates the heme iron, and the catalytic pocket residues, together, determine the reaction selectivity and regio- and stereo-selectivity of the P450 enzymes. Different substrates also affect the properties of P450s by binding to its catalytic pocket. Modulating the redox potential of the heme by substituting iron-coordinating residues changes the chemical reaction, the type of cofactor requirement, and the stereoselectivity of P450s. Around hundreds of P450s are experimentally characterized, therefore, a mechanistic understanding of the factors affecting their catalysis is increasingly vital in the age of synthetic biology and biotechnology. Engineering P450s can enable them to catalyze a variety of chemical reactions viz. oxygenation, peroxygenation, cyclopropanation, epoxidation, nitration, etc., to synthesize high-value chiral organic molecules with exceptionally high stereo- and regioselectivity and catalytic efficiency. This review will focus on recent studies of the mechanistic understandings of the modulation of heme redox potential in the engineered P450 variants, and the effect of small decoy molecules, dual function small molecules, and substrate mimetics on the type of chemical reaction and the catalytic cycle of the P450 enzymes.
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Lei W, Song Y, Long A, Que Y, He S, Zhong H, Chen Y. Stereoselective (4 + 3) cycloadditions of allenyl ethers-furans by chiral auxiliaries inducing and evaluation of anti-breast cancer activity. FRONTIERS IN PLANT SCIENCE 2022; 13:1087899. [PMID: 36618658 PMCID: PMC9812524 DOI: 10.3389/fpls.2022.1087899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 11/14/2022] [Indexed: 06/17/2023]
Abstract
The medicinal plants were wildly library of natural products in drug discovery. The most active molecules with seven-membered rings skeleton represent a challenge for construction. A stereoselectivity (4 + 3) cycloadditions between allenyl ethers and substituted furans induced by chiral auxiliaries has been investigated. And the results showed significant stereoselectivities and regioselectivities. The optical cycloadducts with an oxygen-substituted seven-membered ring framework were generated by removing chiral auxiliaries under acidic conditions. The antiproliferative activity of the novel compounds displayed moderate antiproliferative effects toward T47D cells.
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Ashworth MA, Bombino E, de Jong RM, Wijma HJ, Janssen DB, McLean KJ, Munro AW. Computation-Aided Engineering of Cytochrome P450 for the Production of Pravastatin. ACS Catal 2022; 12:15028-15044. [PMID: 36570080 PMCID: PMC9764288 DOI: 10.1021/acscatal.2c03974] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 10/22/2022] [Indexed: 11/29/2022]
Abstract
CYP105AS1 is a cytochrome P450 from Amycolatopsis orientalis that catalyzes monooxygenation of compactin to 6-epi-pravastatin. For fermentative production of the cholesterol-lowering drug pravastatin, the stereoselectivity of the enzyme needs to be inverted, which has been partially achieved by error-prone PCR mutagenesis and screening. In the current study, we report further optimization of the stereoselectivity by a computationally aided approach. Using the CoupledMoves protocol of Rosetta, a virtual library of mutants was designed to bind compactin in a pro-pravastatin orientation. By examining the frequency of occurrence of beneficial substitutions and rational inspection of their interactions, a small set of eight mutants was predicted to show the desired selectivity and these variants were tested experimentally. The best CYP105AS1 variant gave >99% stereoselective hydroxylation of compactin to pravastatin, with complete elimination of the unwanted 6-epi-pravastatin diastereomer. The enzyme-substrate complexes were also examined by ultrashort molecular dynamics simulations of 50 × 100 ps and 5 × 22 ns, which revealed that the frequency of occurrence of near-attack conformations agreed with the experimentally observed stereoselectivity. These results show that a combination of computational methods and rational inspection could improve CYP105AS1 stereoselectivity beyond what was obtained by directed evolution. Moreover, the work lays out a general in silico framework for specificity engineering of enzymes of known structure.
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Xu X, Xu R, Hou S, Kang Z, Lü C, Wang Q, Zhang W, Wang X, Xu P, Gao C, Ma C. A Selective Fluorescent l-Lactate Biosensor Based on an l-Lactate-Specific Transcription Regulator and Förster Resonance Energy Transfer. BIOSENSORS 2022; 12:1111. [PMID: 36551077 PMCID: PMC9775004 DOI: 10.3390/bios12121111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 11/21/2022] [Accepted: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Selective detection of l-lactate levels in foods, clinical, and bacterial fermentation samples has drawn intensive attention. Many fluorescent biosensors based on non-stereoselective recognition elements have been developed for lactate detection. Herein, the allosteric transcription factor STLldR from Salmonella enterica serovar Typhimurium LT2 was identified to be stereo-selectively respond to l-lactate. Then, STLldR was combined with Förster resonance energy transfer (FRET) to construct a fluorescent l-lactate biosensor FILLac. FILLac was further optimized by truncating the N- and C-terminal amino acids of STLldR between cyan and yellow fluorescent proteins. The optimized biosensor FILLac10N0C exhibited a maximum emission ratio change (ΔRmax) of 33.47 ± 1.91%, an apparent dissociation constant (Kd) of 6.33 ± 0.79 μM, and a limit of detection of 0.68 μM. FILLac10N0C was applied in 96-well microplates to detect l-lactate in bacterial fermentation samples and commercial foods such as Jiaosu and yogurt. The quantitation results of FILLac10N0C exhibited good agreement with that of a commercial l-lactate biosensor SBA-40D bioanalyzer. Thus, the biosensor FILLac10N0C compatible with high-throughput detection may be a potential choice for quantitation of l-lactate in different biological samples.
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The Origin of Stereoselectivity in the Hydrogenation of Oximes Catalyzed by Iridium Complexes: A DFT Mechanistic Study. Molecules 2022; 27:molecules27238349. [PMID: 36500448 PMCID: PMC9737400 DOI: 10.3390/molecules27238349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 11/23/2022] [Accepted: 11/25/2022] [Indexed: 12/05/2022] Open
Abstract
Herein the reaction mechanism and the origin of stereoselectivity of asymmetric hydrogenation of oximes to hydroxylamines catalyzed by the cyclometalated iridium (III) complexes with chiral substituted single cyclopentadienyl ligands (Ir catalysts A1 and B1) under acidic condition were unveiled using DFT calculations. The catalytic cycle for this reaction consists of the dihydrogen activation step and the hydride transfer step. The calculated results indicate that the hydride transfer step is the chirality-determining step and the involvement of methanesulfonate anion (MsO-) in this reaction is of importance in the asymmetric hydrogenation of oximes catalyzed by A1 and B1. The calculated energy barriers for the hydride transfer steps without an MsO- anion are higher than those with an MsO- anion. The differences in Gibbs free energies between TSA5-1fR/TSA5-1fS and TSB5-1fR/TSB5-1fS are 13.8/13.2 (ΔΔG‡ = 0.6 kcal/mol) and 7.5/5.6 (ΔΔG‡ = 1.9 kcal/mol) kcal/mol for the hydride transfer step of substrate protonated oximes with E configuration (E-2a-H+) with MsO- anion to chiral hydroxylamines product R-3a/S-3a catalyzed by A1 and B1, respectively. According to the Curtin-Hammet principle, the major products are hydroxylamines S-3a for the reaction catalyzed by A1 and B1, which agrees well with the experimental results. This is due to the non-covalent interactions among the protonated substrate, MsO- anion and catalytic species. The hydrogen bond could not only stabilize the catalytic species, but also change the preference of stereoselectivity of this reaction.
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Kumagai K, Sakai S, Ueno M, Kataoka M, Kobayashi S, Hanada K. Chlamydial Infection-Dependent Synthesis of Sphingomyelin as a Novel Anti-Chlamydial Target of Ceramide Mimetic Compounds. Int J Mol Sci 2022; 23:ijms232314697. [PMID: 36499025 PMCID: PMC9735676 DOI: 10.3390/ijms232314697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 11/09/2022] [Accepted: 11/17/2022] [Indexed: 11/27/2022] Open
Abstract
The obligate intracellular bacterium Chlamydia trachomatis is the major causative agent of bacterial sexually transmitted diseases worldwide. In infected cells, the ceramide transport protein (CERT) is recruited to inclusions, where C. trachomatis replicates using host-synthesized ceramide. The ceramide is converted to sphingomyelin (SM) by a chlamydial infection-dependent SM synthesis (cidSM-synthesis) pathway, which occurs even in the absence of the SM synthases (SMS)-1 and -2 of host cells. The ceramide mimetic compound (1R,3S)-HPA-12 and the nonmimetic compound E16A, both of which are potent inhibitors of CERT, repressed the proliferation of C. trachomatis in HeLa cells. Unexpectedly, (1R,3R)-HPA-12, a ceramide mimetic compound that lacks CERT inhibitory activity, also exhibited potent anti-chlamydial activity. Using endogenous SMS-knockout mutant HeLa cells, we revealed that (1R,3R)-HPA-12 mildly inhibited cidSM-synthesis. In addition, LC-MS analysis revealed that (1R,3R)-HPA-12 is converted to a phosphocholine-conjugated metabolite in an infection-dependent manner. Imaging analysis with a fluorescent analog of ceramide suggested that cidSM-synthesis occurs in the bacterial bodies and/or inclusions. Collectively, these results suggested that (1R,3R)-HPA-12 exerts its anti-chlamydia activity not only as an inhibitor of cidSM-synthesis, but also via putative toxic effects of its phosphocholine adduct, which is most likely produced by the cidSM-synthesis route.
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Gregori BJ, Schmotz MWS, Jacobi von Wangelin A. Stereoselective Semi-Hydrogenations of Alkynes by First-Row (3d) Transition Metal Catalysts. ChemCatChem 2022; 14:e202200886. [PMID: 36632425 PMCID: PMC9825939 DOI: 10.1002/cctc.202200886] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/25/2022] [Indexed: 01/14/2023]
Abstract
The chemo- and stereoselective semi-hydrogenation of alkynes to alkenes is a fundamental transformation in synthetic chemistry, for which the use of precious 4d or 5d metal catalysts is well-established. In mankind's unwavering quest for sustainability, research focus has considerably veered towards the 3d metals. Given their high abundancy and availability as well as lower toxicity and noxiousness, they are undoubtedly attractive from both an economic and an environmental perspective. Herein, we wish to present noteworthy and groundbreaking examples for the use of 3d metal catalysts for diastereoselective alkyne semi-hydrogenation as we embark on a journey through the first-row transition metals.
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Spahić Z, Hrenar T, Primožič I. Polytopal Rearrangement Governing Stereochemistry of Bicyclic Oxime Ether Synthesis. Int J Mol Sci 2022; 23:ijms232012331. [PMID: 36293187 PMCID: PMC9604001 DOI: 10.3390/ijms232012331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/10/2022] [Accepted: 10/13/2022] [Indexed: 11/05/2022] Open
Abstract
In the present study, four O-substituted oximes of quinuclidin-3-one were synthesized using appropriate O-substituted hydroxylamine hydrochlorides. In order to perform these reactions in a solvent, a mixture of (E) and (Z) products was yielded. Using mechanochemical and microwave synthesis, we then obtained pure (E) oximes. In almost all cases, the conversion to oxime ethers was completed. Reactions were monitored by ATR spectroscopy and the ratios of (E) and (Z) oxime ethers were deduced from 1H NMR data. Several reactions were very rapid (1 min) with 100% conversion and stereospecificity. To investigate the reaction mechanisms, full conformational analyses of the reaction intermediates were performed and the lowest energy conformers were determined. These conformers differed in spatial arrangement around the nitrogen atom of the amino group and were in the correct orientation for reactions to occur. Calculated standard Gibbs energies of the formation were in agreement with the experimentally obtained ratios of (E) and (Z) isomers. This work shows alternatives to the classical synthesis of O-substituted oxime ether precursors and highlights the fast reaction rate and stereoselectivity of microwave synthesis as well as the “green” aspects of mechanochemistry.
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Sun X, Hinz A, Kucher H, Gamer MT, Roesky PW. Stereoselective Activation of Small Molecules by a Stable Chiral Silene. Chemistry 2022; 28:e202201963. [PMID: 35762907 DOI: 10.1002/chem.202201963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Indexed: 01/07/2023]
Abstract
The reaction of the dilithium salt of the enantiopure (S)-BINOL (1,1'-bi-2-naphthol) with two equivalents of the amidinate-stabilized chlorosilylene [LPh SiCl] (LPh =PhC(NtBu)2 ) led to the formation of the first example of a chiral cyclic silene species comprising an (S)-BINOL ligand. The reactivity of the Si=C bond was investigated by reaction with elemental sulfur, CO2 and HCl. The reaction with S8 led to a Si=C bond cleavage and concomitantly to a ring-opened product with imine and silanethione functional groups. The reaction with CO2 resulted in the cleavage of the CO2 molecule into a carbonyl group and an isolated O atom, while a new stereocenter is formed in a highly selective manner. According to DFT calculations, the [2+2] cycloaddition product is the key intermediate. Further reactivity studies of the chiral cyclic silene with HCl resulted in a stereoselective addition to the Si=C bond, while the fully selective formation of two stereocenters was achieved. The quantitative stereoselective addition of CO2 and HCl to a Si=C bond is unprecedented.
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Yang F, Liu S, Wolber G, Bureik M, Parr MK. Complete Reaction Phenotyping of Propranolol and 4-Hydroxypropranolol with the 19 Enzymes of the Human UGT1 and UGT2 Families. Int J Mol Sci 2022; 23:ijms23137476. [PMID: 35806479 PMCID: PMC9267274 DOI: 10.3390/ijms23137476] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 06/27/2022] [Accepted: 06/29/2022] [Indexed: 02/01/2023] Open
Abstract
Propranolol is a competitive non-selective beta-receptor antagonist that is available on the market as a racemic mixture. In the present study, glucuronidation of propranolol and its equipotent phase I metabolite 4-hydroxypropranolol by all 19 members of the human UGT1 and UGT2 families was monitored. UGT1A7, UGT1A9, UGT1A10 and UGT2A1 were found to glucuronidate propranolol, with UGT1A7, UGT1A9 and UGT2A1 mainly acting on (S)-propranolol, while UGT1A10 displays the opposite stereoselectivity. UGT1A7, UGT1A9 and UGT2A1 were also found to glucuronidate 4-hydroxypropranolol. In contrast to propranolol, 4-hydroxypropranolol was found to be glucuronidated by UGT1A8 but not by UGT1A10. Additional biotransformations with 4-methoxypropanolol demonstrated different regioselectivities of these UGTs with respect to the aliphatic and aromatic hydroxy groups of the substrate. Modeling and molecular docking studies were performed to explain the stereoselective glucuronidation of the substrates under study.
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Nasti R, Bassanini I, Ferrandi EE, Linguardo F, Bertuletti S, Vanoni M, Riva S, Verotta L, Monti D. Stereoselective Biocatalyzed Reductions of Ginger Active Components Recovered from Industrial Wastes. Chembiochem 2022; 23:e202200105. [PMID: 35188325 PMCID: PMC9314113 DOI: 10.1002/cbic.202200105] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Indexed: 11/30/2022]
Abstract
Ginger is among the most widespread and widely consumed traditional medicinal plants around the world. Its beneficial effects, which comprise e. g. anticancer and anti-inflammatory activities as well as gastrointestinal regulatory effects, are generally attributed to a family of non-volatile compounds characterized by an arylalkyl long-chained alcohol, diol, or ketone moiety. In this work, ginger active components have been successfully recovered from industrial waste biomass of fermented ginger. Moreover, their recovery has been combined with the first systematic study of the stereoselective reduction of gingerol-like compounds by isolated alcohol dehydrogenases (ADHs), obtaining the enantioenriched sec-alcohol derivatives via a sustainable biocatalytic path in up to >99 % conversions and >99 % enantiomeric/diastereomeric excesses.
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Reetz MT. Making Enzymes Suitable for Organic Chemistry by Rational Protein Design. Chembiochem 2022; 23:e202200049. [PMID: 35389556 PMCID: PMC9401064 DOI: 10.1002/cbic.202200049] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 04/07/2022] [Indexed: 11/25/2022]
Abstract
This review outlines recent developments in protein engineering of stereo‐ and regioselective enzymes, which are of prime interest in organic and pharmaceutical chemistry as well as biotechnology. The widespread application of enzymes was hampered for decades due to limited enantio‐, diastereo‐ and regioselectivity, which was the reason why most organic chemists were not interested in biocatalysis. This attitude began to change with the advent of semi‐rational directed evolution methods based on focused saturation mutagenesis at sites lining the binding pocket. Screening constitutes the labor‐intensive step (bottleneck), which is the reason why various research groups are continuing to develop techniques for the generation of small and smart mutant libraries. Rational enzyme design, traditionally an alternative to directed evolution, provides small collections of mutants which require minimal screening. This approach first focused on thermostabilization, and did not enter the field of stereoselectivity until later. Computational guides such as the Rosetta algorithms, HotSpot Wizard metric, and machine learning (ML) contribute significantly to decision making. The newest advancements show that semi‐rational directed evolution such as CAST/ISM and rational enzyme design no longer develop on separate tracks, instead, they have started to merge. Indeed, researchers utilizing the two approaches have learned from each other. Today, the toolbox of organic chemists includes enzymes, primarily because the possibility of controlling stereoselectivity by protein engineering has ensured reliability when facing synthetic challenges. This review was also written with the hope that undergraduate and graduate education will include enzymes more so than in the past.
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Fukaya M, Ozaki T, Minami A, Oikawa H. Biosynthetic machineries of anthraquinones and bisanthraquinones in Talaromyces islandicus. Biosci Biotechnol Biochem 2022; 86:435-443. [PMID: 35108363 DOI: 10.1093/bbb/zbac009] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2021] [Accepted: 01/13/2022] [Indexed: 11/13/2022]
Abstract
Talaromyces islandicus is a unique fungus that produces more than 20 numbers of anthraquinones (AQs) and their dimeric natural products, bisanthraquinones (BQs). These compounds share a 9,10-anthracenedione core derived from emodin. The biosynthetic pathway of emodin has been firmly established, while that of other AQs and BQs is still unclear. In this study, we identified the biosynthetic gene clusters for chrysophanol and skyrin. The function of key modification enzymes was examined by performing biotransformation experiments and in vitro enzymatic reactions with emodin and its derivatives, allowing us to propose a mechanism for the modification reactions. The present study provides insight into the biosynthesis of AQs and BQs in T. islandicus.
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Vashistha VK. Detection and remediation of chiral pharmaceuticals from wastewater: A review. Chirality 2022; 34:833-847. [PMID: 35285083 DOI: 10.1002/chir.23437] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/24/2022] [Accepted: 02/26/2022] [Indexed: 11/06/2022]
Abstract
Chiral organic pollutants including pharmaceuticals, pesticides, herbicides, flame retardants, and polycyclic musk cause significant risks to both the environment and human health. Chiral pharmaceuticals (CPs) are among the significant class of pseudo-persistent substances that have been observed in the concentration level from nanomolar to micromolar quantities and cause bad impacts on nontargeted species and direct or indirect human health issues due to water and foodborne contamination. The CPs may contain one or more chiral centers in their structural framework and thus enantiomers of CPs often possess different distribution, fate, bioaccumulation potential, and toxicity. The enantioselective chromatographic techniques have been extensively applied to detect drug enantiomers during the last few years. Bioremediation techniques offer unique characteristics above conventional remediation procedures as these could be cost-effective and accomplish total organic pollutant decomposition without causing collateral damage to the site material or native flora and fauna. This review describes the impacts of chiral pharmaceuticals on the environment; detection technologies (particularly liquid chromatography), and important remedial measures for safer disposal of such pollutants.
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Wen M, Erb W, Mongin F, Halauko YS, Ivashkevich OA, Matulis VE, Roisnel T. Synthesis of Polysubstituted Ferrocenesulfoxides. Molecules 2022; 27:molecules27061798. [PMID: 35335161 PMCID: PMC8955965 DOI: 10.3390/molecules27061798] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/04/2022] [Accepted: 03/05/2022] [Indexed: 01/21/2023] Open
Abstract
The purpose of the study is to design synthetic methodologies, especially directed deprotometalation using polar organometallic reagents, to access polysubstituted ferrocenesulfoxides. From enantiopure 2-substituted (SiMe3, PPh2) S-tert-butylferrocenesulfoxides, a third substituent was first introduced at the 5 position (SiMe3, I, D, C(OH)Ph2, Me, PPh2, CH2NMe2, F) and removal of the trimethylsilyl group then afforded 2-substituted ferrocenesulfoxides unreachable otherwise. Attempts to apply the “halogen dance” reaction to the ferrocenesulfoxide series led to unexpected results although rationalized in light of calculated pKa values. Further functionalizations were also possible. Thus, new enantiopure, planar chiral di- and trisubstituted ferrocenes have been obtained, in addition to several original 2-substituted, 2,3- and 2,5-disubstituted, 2,3,5-trisubstituted and even 2,3,4,5-tetrasubstituted ferrocenesulfoxides, also enantiopure.
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Patti A, Sanfilippo C. Stereoselective Promiscuous Reactions Catalyzed by Lipases. Int J Mol Sci 2022; 23:ijms23052675. [PMID: 35269815 PMCID: PMC8910291 DOI: 10.3390/ijms23052675] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 02/25/2022] [Accepted: 02/25/2022] [Indexed: 01/27/2023] Open
Abstract
The ability of lipases to display activity beyond their physiological reactions, so-called "catalytic promiscuity", has gained increasing interest in the last two decades as an important tool for expanding the application of these enzymes in organic synthesis. Some lipases have been shown to be effective in catalyzing a variety of C-C bond formation reactions and most of the investigations have been directed to the optimization of the products yield through a careful tuning of the experimental parameters. Despite the fact that new stereogenic carbons are formed in many of the tested reactions, the target products have been often obtained in racemic form and examples of an efficient asymmetric induction by the used lipases are quite limited. The aim of this review, mainly focused on those lipase-catalyzed promiscuous reactions in which optically active products have been obtained, is to offer a current state of art together with a perspective in this field of asymmetric synthesis.
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Environmental Modulation of Chiral Prolinamide Catalysts for Stereodivergent Conjugate Addition. J Catal 2022; 406:126-133. [PMID: 35087258 PMCID: PMC8788998 DOI: 10.1016/j.jcat.2022.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Synthetic chiral catalysts generally rely on proximal functional groups or ligands for chiral induction. Enzymes often employ environmental chirality to achieve stereoselectivity. Environmentally controlled catalysis has benefits such as size and shape selectivity but is underexplored by chemists. We here report molecularly imprinted nanoparticles (MINPs) that utilized their environmental chirality to either augment or reverse the intrinsic selectivity of a chiral prolinamide cofactor. The latter ability allowed the catalyst to produce products otherwise disfavored in the conjugate addition of aldehyde to nitroalkene. The catalysis occurred in water at room temperature and afforded γ-nitroaldehydes with excellent yields (up to 94%) and ee (>90% in most cases). Up to 25:1 syn/anti and 1:6 syn/anti ratios were achieved through a combination of catalyst-derived and environmentally enabled selectivity. The high enantioselectivity of the MINP also made it possible for racemic catalysts to perform asymmetric catalysis, with up to 80% ee for the conjugate addition.
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70
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Qin Y, Wang S, Wen Q, Xia Q, Wang S, Chen G, Sun J, Shen C, Song S. Corrigendum: Interactions Between Ephedra sinica and Prunus armeniaca: From Stereoselectivity to Deamination as a Metabolic Detoxification Mechanism of Amygdalin. Front Pharmacol 2022; 12:831921. [PMID: 35069226 PMCID: PMC8766829 DOI: 10.3389/fphar.2021.831921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 12/10/2021] [Indexed: 11/13/2022] Open
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71
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Liu C, Gao Q, Shang Z, Liu J, Zhou S, Dang J, Liu L, Lange I, Srividya N, Lange BM, Wu Q, Lin W. Corrigendum: Functional Characterization and Structural Insights Into Stereoselectivity of Pulegone Reductase in Menthol Biosynthesis. FRONTIERS IN PLANT SCIENCE 2022; 12:828351. [PMID: 35095991 PMCID: PMC8796687 DOI: 10.3389/fpls.2021.828351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 12/27/2021] [Indexed: 06/14/2023]
Abstract
[This corrects the article DOI: 10.3389/fpls.2021.780970.].
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72
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Synthesis of C2-Alkoxy-Substituted 19-Nor Vitamin D 3 Derivatives: Stereoselectivity and Biological Activity. Biomolecules 2022; 12:biom12010069. [PMID: 35053217 PMCID: PMC8773602 DOI: 10.3390/biom12010069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 12/29/2021] [Accepted: 12/30/2021] [Indexed: 11/17/2022] Open
Abstract
The active form of vitamin D3 (D3), 1a,25-dihydroxyvitamn D3 (1,25D3), plays a central role in calcium and bone metabolism. Many structure–activity relationship (SAR) studies of D3 have been conducted, with the aim of separating the biological activities of 1,25D3 or reducing its side effects, such as hypercalcemia, and SAR studies have shown that the hypercalcemic activity of C2-substituted derivatives and 19-nor type derivatives is significantly suppressed. In the present paper, we describe the synthesis of 19-nor type 1,25D3 derivatives with alkoxy groups at C2, by means of the Julia–Kocienski type coupling reaction between a C2 symmetrical A ring ketone and a CD ring synthon. The effect of C2 substituents on the stereoselectivity of the coupling reaction was evaluated. The biological activities of the synthesized derivatives were evaluated in an HL-60 cell-based assay. The a-methoxy-substituted C2α-7a was found to show potent cell-differentiating activity, with an ED50 value of 0.38 nM, being 26-fold more potent than 1,25D3.
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73
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Arora R, Rodríguez JF, Whyte A, Lautens M. Accessing Unsymmetrically Linked Heterocycles through Stereoselective Palladium-Catalyzed Domino Cyclization. Angew Chem Int Ed Engl 2022; 61:e202112288. [PMID: 34739741 DOI: 10.1002/anie.202112288] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Indexed: 12/23/2022]
Abstract
A palladium-catalyzed strategy is presented to synthesize unsymmetrically linked heterocycles within stereoselective tetrasubstituted olefins. This reaction is proposed to occur via a vinyl-PdII intermediate capable of initiating the cyclization of various alkyne-tethered nucleophiles. Products are formed in up to 96 % yield and excellent stereoselectivities are obtained using low catalyst loadings. This transformation was scalable up to 1 mmol and mechanistic studies suggest a syn-carbopalladation of the carbamoyl chloride followed by PdII -catalyzed cyclization of alkyne-tethered nucleophiles.
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74
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Merx J, Houthuijs KJ, Elferink H, Witlox E, Mecinović J, Oomens J, Martens J, Boltje TJ, Rutjes FPJT. Characterization of Cyclic N-Acyliminium Ions by Infrared Ion Spectroscopy. Chemistry 2021; 28:e202104078. [PMID: 34911145 PMCID: PMC9302692 DOI: 10.1002/chem.202104078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Indexed: 11/10/2022]
Abstract
N‐Acyliminium ions are highly reactive intermediates that are important for creating CC‐bonds adjacent to nitrogen atoms. Here we report the characterization of cyclic N‐acyliminium ions in the gas phase, generated by collision induced dissociation tandem mass spectrometry followed by infrared ion spectroscopy using the FELIX infrared free electron laser. Comparison of DFT calculated spectra with the experimentally observed IR spectra provided valuable insights in the conformations of the N‐acyliminium ions.
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75
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Stockinger P, Borlinghaus N, Sharma M, Aberle B, Grogan G, Pleiss J, Nestl BM. Inverting the Stereoselectivity of an NADH-Dependent Imine-Reductase Variant. ChemCatChem 2021; 13:5210-5215. [PMID: 35873105 PMCID: PMC9297850 DOI: 10.1002/cctc.202101057] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/12/2021] [Indexed: 12/31/2022]
Abstract
Imine reductases (IREDs) offer biocatalytic routes to chiral amines and have a natural preference for the NADPH cofactor. In previous work, we reported enzyme engineering of the (R)-selective IRED from Myxococcus stipitatus (NADH-IRED-Ms) yielding a NADH-dependent variant with high catalytic efficiency. However, no IRED with NADH specificity and (S)-selectivity in asymmetric reductions has yet been reported. Herein, we applied semi-rational enzyme engineering to switch the selectivity of NADH-IRED-Ms. The quintuple variant A241V/H242Y/N243D/V244Y/A245L showed reverse stereopreference in the reduction of the cyclic imine 2-methylpyrroline compared to the wild-type and afforded the (S)-amine product with >99 % conversion and 91 % enantiomeric excess. We also report the crystal-structures of the NADPH-dependent (R)-IRED-Ms wild-type enzyme and the NADH-dependent NADH-IRED-Ms variant and molecular dynamics (MD) simulations to rationalize the inverted stereoselectivity of the quintuple variant.
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