1
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Lemler PM, Craft CL, Pollok CH, Regan TP, Vaccaro PH. Isolated and solvated chiroptical behavior in conformationally flexible butanamines. Chirality 2023; 35:586-618. [PMID: 37550220 DOI: 10.1002/chir.23570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 04/15/2023] [Accepted: 04/17/2023] [Indexed: 08/09/2023]
Abstract
The nonresonant optical activity of two highly flexible aliphatic amines, (2R)-3-methyl-2-butanamine (R-MBA) and (2R)-(3,3)-dimethyl-2-butanamine (R-DMBA), has been probed under isolated and solvated conditions to examine the roles of conformational isomerism and to explore the influence of extrinsic perturbations. The optical rotatory dispersion (ORD) measured in six solvents presented uniformly negative rotatory powers over the 320-590 nm region, with the long-wavelength magnitude of chiroptical response growing nearly monotonically as the dielectric constant of the surroundings diminished. The intrinsic specific optical rotation,α λ T (in deg dm-1 [g/mL]-1 ), extracted for ambient vapor-phase samples of R-MBA [-11.031(98) and -2.29 (11)] and R-DMBA [-9.434 (72) and -1.350 (48)] at 355 and 633 nm were best reproduced by counterintuitive solvents of high polarity (yet low polarizability) like acetonitrile and methanol. Attempts to interpret observed spectral signatures quantitatively relied on the linear-response frameworks of density-functional theory (B3LYP, cam-B3LYP, and dispersion-corrected analogs) and coupled-cluster theory (CCSD), with variants of the polarizable continuum model (PCM) deployed to account for the effects of implicit solvation. Building on the identification of several low-lying equilibrium geometries (nine for R-MBA and three for R-DMBA), ensemble-averaged ORD profiles were calculated at T = 300 K by means of the independent-conformer ansatz, which enabled response properties predicted for the optimized structure of each isomer to be combined through Boltzmann-weighted population fractions derived from corresponding relative internal-energy or free-energy values, the latter of which stemmed from composite CBS-APNO and G4 analyses. Although reasonable accord between theory and experiment was realized for the isolated (vapor-phase) species, the solution-phase results were less satisfactory and tended to degrade progressively as the solvent polarity increased. These trends were attributed to solvent-mediated changes in structural parameters and energy metrics for the transition states that separate and putatively isolate the equilibrium conformations supported by the ground electronic potential-energy surface, with the resulting displacement of barrier locations and/or decrease of barrier heights compromising the underlying premise of the independent-conformer ansatz.
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Affiliation(s)
- Paul M Lemler
- Department of Chemistry, Yale University, New Haven, Connecticut, USA
- Intel Corporation, Hillsboro, Oregon, USA
| | - Clayton L Craft
- Department of Chemistry, Yale University, New Haven, Connecticut, USA
- United States Air Force Research Laboratory, Rome, New York, USA
| | - Corina H Pollok
- Department of Chemistry, Yale University, New Haven, Connecticut, USA
- Organische Chemie II, Ruhr-Universität Bochum, Bochum, Germany
| | - Thomas P Regan
- Department of Chemistry, Yale University, New Haven, Connecticut, USA
| | - Patrick H Vaccaro
- Department of Chemistry, Yale University, New Haven, Connecticut, USA
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2
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Monti M, Brancolini G, Coccia E, Toffoli D, Fortunelli A, Corni S, Aschi M, Stener M. The Conformational Dynamics of the Ligands Determines the Electronic Circular Dichroism of the Chiral Au 38(SC 2H 4Ph) 24 Cluster. J Phys Chem Lett 2023; 14:1941-1948. [PMID: 36787099 PMCID: PMC9940292 DOI: 10.1021/acs.jpclett.2c03923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 02/10/2023] [Indexed: 06/18/2023]
Abstract
Effects of the conformational dynamics of 2-PET protective ligands on the electronic circular dichroism (ECD) of the chiral Au38(SC2H4Ph)24 cluster are investigated. We adopt a computational protocol in which ECD spectra are calculated via the first principle polTDDFT approach on a series of conformations extracted from MD simulations by using Essential Dynamics (ED) analysis, and then properly weighted to predict the final spectrum. We find that the experimental spectral features are well reproduced, whereas significant discrepancies arise when the spectrum is calculated using the experimental X-ray structure. This result unambiguously demonstrates the need to account for the conformational effects in the ECD modeling of chiral nanoclusters. The present procedure proved to be able of capturing the essential conformational features of the dynamic Au38(SC2H4Ph)24 system, opening the possibility to model the ECD of soluble chiral nanoclusters in a realistic way.
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Affiliation(s)
- M. Monti
- Dipartimento
di Scienze Chimiche e Farmaceutiche, Università
di Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy
| | - G. Brancolini
- Istituto
Nanoscienze, CNR-NANO, Center S3, Via G. Campi 213/A, 41100 Modena, Italy
| | - E. Coccia
- Dipartimento
di Scienze Chimiche e Farmaceutiche, Università
di Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy
| | - D. Toffoli
- Dipartimento
di Scienze Chimiche e Farmaceutiche, Università
di Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy
| | - A. Fortunelli
- CNR-ICCOM, Consiglio Nazionale delle Ricerche, via G. Moruzzi 1, 56124, Pisa, Italy
| | - S. Corni
- Istituto
Nanoscienze, CNR-NANO, Center S3, Via G. Campi 213/A, 41100 Modena, Italy
- Dipartimento
di Scienze Chimiche, Università di
Padova, Via Francesco Marzolo 1, 35131 Padova, Italy
| | - M. Aschi
- Dipartimento
di Scienze Fisiche e Chimiche, Università
dell’Aquila, Via Vetoio, 67100, l’Aquila, Italy
| | - M. Stener
- Dipartimento
di Scienze Chimiche e Farmaceutiche, Università
di Trieste, Via L. Giorgieri 1, 34127 Trieste, Italy
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3
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Zullo V, Górecki M, Guazzelli L, Mezzetta A, Pescitelli G, Iuliano A. Exploiting isohexide scaffolds for the preparation of chiral ionic liquids tweezers. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114528] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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4
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Górecki M, Zullo V, Iuliano A, Pescitelli G. On the Absolute Stereochemistry of Tolterodine: A Circular Dichroism Study. Pharmaceuticals (Basel) 2019; 12:ph12010021. [PMID: 30691175 PMCID: PMC6469158 DOI: 10.3390/ph12010021] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 01/18/2019] [Accepted: 01/22/2019] [Indexed: 02/06/2023] Open
Abstract
Tolterodine (1) is a potent muscarinic receptor antagonist used in the treatment of overactive urinary bladder (OAB) syndrome. Tolterodine is chiral and it was patented, and is currently marketed, as the l-tartrate salt of the (R)-enantiomer. However, the existing literature does not offer an ultimate proof of a stereoselective mode of action of 1. A second open stereochemical issue concerns the absolute configuration (AC) of 1. Neither the original patents nor subsequent studies have established the AC of 1 in an unambiguous way, although the AC of the l-tartrate salt of 1 was assigned by X-ray diffractometry. Finally, neither electronic nor vibrational circular dichroism (ECD and VCD) spectra of 1 are reported so far. We performed a thorough ECD/VCD study of 1 in different solvents and at variable temperatures. Solvent and temperature dependence highlighted the existence of moderate flexibility which was confirmed by molecular modelling. ECD calculations with time-dependent density functional theory (TDDFT) accurately reproduced the experimental spectra and allowed us to confirm the AC of 1 in an independent way.
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Affiliation(s)
- Marcin Górecki
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy.
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52 St., 01-224 Warsaw, Poland.
| | - Valerio Zullo
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy.
| | - Anna Iuliano
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy.
| | - Gennaro Pescitelli
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 13, 56124 Pisa, Italy.
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5
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Rode JE, Górecki M, Witkowski S, Frelek J. Solvation of 2-(hydroxymethyl)-2,5,7,8-tetramethyl-chroman-6-ol revealed by circular dichroism: a case of chromane helicity rule breaking. Phys Chem Chem Phys 2018; 20:22525-22536. [PMID: 30140796 DOI: 10.1039/c8cp02491j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The primary goal of this work is to clarify why 2-(hydroxymethyl)-2,5,7,8-tetramethyl-chroman-6-ol {(S)-TMChM} deviates from the chromane helicity rule under solvent change. The rule, applicable to determining the absolute configuration of molecules containing the chromane chromophore, binds the sign of the 1Lb Cotton effect (CE) with the helicity of the dihydropyran ring. In case of TMChM, however, this CE exhibits extreme solvent dependence: it is negative in non-coordinating solvents and positive in coordinating ones, irrespective of the helicity of the heterocyclic ring. TD-DFT calculations using PCM and hybrid solvation models were performed to explain origin of this phenomenon. It turned out that the 1Lb CE sign directly depends on the position of the phenolic OH group at carbon atom C6 (OHC6). In the absence of interactions with solvents (as in CCl4 or nC6H14) or when a solvent plays proton donor role (as in CHCl3), the OHC6 lies in the phenyl plane and the 1Lb CE sign follows the P/M helicity rule. In contrast, in proton acceptor solvents, like DMSO, CH3OH or CH3CN, the OHC6 group is deflected from the phenyl plane, and the 1Lb CE sign of individual (S)-TMChM conformers depends on the sector in which the OHC6 is located. Thus, in solution, the 1Lb CE sign is an average over different orientations of the OHC6 group and can be positive (as in DMSO and CH3OH) or negative (as in CH3CN) which means that it does not follow the chromane helicity rule. The impact of OHC6 on the 1Lb CE sign and thus the conclusions for the stereochemistry of chromans are demonstrated here for the first time. Additionally, a comparison of experimental and simulated ECD spectra, supported by VCD data, allowed to determine the geometry of intermolecular clusters formed in different solvents.
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Affiliation(s)
- Joanna E Rode
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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6
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Diverse Secondary Metabolites from the Marine-Derived Fungus Dichotomomyces cejpii F31-1. Mar Drugs 2017; 15:md15110339. [PMID: 29104243 PMCID: PMC5706029 DOI: 10.3390/md15110339] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 10/25/2017] [Accepted: 10/26/2017] [Indexed: 12/14/2022] Open
Abstract
By adding l-tryptophan and l-phenylalanine to GPY medium, twenty-eight compounds, including amides, polyketides, a sesquiterpenoid, a diterpenoid, a meroterpenoid, diketopiperazines, β-carbolines, fumiquinazolines, and indole alkaloids, were discovered from the marine-derived fungus Dichotomomyces cejpii F31-1, demonstrating the tremendous biosynthetic potential of this fungal strain. Among these compounds, four amides dichotomocejs A–D (1–4), one polyketide dichocetide A (5), and two diketopiperazines dichocerazines A–B (15 and 16) are new. The structures of these new compounds were determined by interpreting detailed spectroscopic data as well as calculating optical rotation values and ECD spectra. Obviously, Dichotomomyces cejpii can effectively use an amino acid-directed strategy to enhance the production of nitrogen-containing compounds. Dichotomocej A (1) displayed moderate cytotoxicity against the human rhabdomyosarcoma cell line RD with an IC50 value of 39.1 µM, and pityriacitrin (22) showed moderate cytotoxicity against the human colon carcinoma cell line HCT116 with an IC50 value of 35.1 µM.
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7
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Haghdani S, Hoff BH, Koch H, Åstrand PO. Solvent Effects on Optical Rotation: On the Balance between Hydrogen Bonding and Shifts in Dihedral Angles. J Phys Chem A 2017; 121:4765-4777. [DOI: 10.1021/acs.jpca.6b12149] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shokouh Haghdani
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Bård Helge Hoff
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Henrik Koch
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
| | - Per-Olof Åstrand
- Department of Chemistry, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway
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8
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Srebro-Hooper M, Autschbach J. Calculating Natural Optical Activity of Molecules from First Principles. Annu Rev Phys Chem 2017; 68:399-420. [DOI: 10.1146/annurev-physchem-052516-044827] [Citation(s) in RCA: 94] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Jochen Autschbach
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260
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9
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Padula D, Cerezo J, Pescitelli G, Santoro F. The shape of the electronic circular dichroism spectrum of (2,6-dimethylphenyl)(phenyl)methanol: interplay between conformational equilibria and vibronic effects. Phys Chem Chem Phys 2017; 19:32349-32360. [DOI: 10.1039/c7cp06369e] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Analysis of the interplay between conformational equilibria, solvent effects and vibronic contributions in the ECD spectra.
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Affiliation(s)
- Daniele Padula
- Department of Chemistry
- University of Liverpool
- Liverpool L69 7ZD
- UK
| | - Javier Cerezo
- Departamento de Química Física
- Universidad de Murcia
- 30100 Murcia
- Spain
| | - Gennaro Pescitelli
- Università di Pisa
- Dipartimento di Chimica e Chimica Industriale
- I-56124 Pisa
- Italy
| | - Fabrizio Santoro
- Consiglio Nazionale delle Ricerche – CNR
- Istituto di Chimica dei Composti Organo Metallici (ICCOM-CNR)
- Pisa
- Italy
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10
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Pescitelli G, Bruhn T. Good Computational Practice in the Assignment of Absolute Configurations by TDDFT Calculations of ECD Spectra. Chirality 2016; 28:466-74. [PMID: 27098594 DOI: 10.1002/chir.22600] [Citation(s) in RCA: 353] [Impact Index Per Article: 44.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 03/03/2016] [Accepted: 03/05/2016] [Indexed: 01/10/2023]
Abstract
Quantum-mechanical calculations of chiroptical properties have rapidly become the most popular method for assigning absolute configurations (AC) of organic compounds, including natural products. Black-box time-dependent Density Functional Theory (TDDFT) calculations of electronic circular dichroism (ECD) spectra are nowadays readily accessible to nonexperts. However, an uncritical attitude may easily deliver a wrong answer. We present to the Chirality Forum a discussion on what can be called good computational practice in running TDDFT ECD calculations, highlighting the most crucial points with several examples from the recent literature. Chirality 28:466-474, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Gennaro Pescitelli
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Pisa, Italy
| | - Torsten Bruhn
- Institut für Organische Chemie, Universität Würzburg Am Hubland, Würzburg, Germany
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11
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Perera AS, Thomas J, Poopari MR, Xu Y. The Clusters-in-a-Liquid Approach for Solvation: New Insights from the Conformer Specific Gas Phase Spectroscopy and Vibrational Optical Activity Spectroscopy. Front Chem 2016; 4:9. [PMID: 26942177 PMCID: PMC4766311 DOI: 10.3389/fchem.2016.00009] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 02/08/2016] [Indexed: 11/30/2022] Open
Abstract
Vibrational optical activity spectroscopies, namely vibrational circular dichroism (VCD) and Raman optical activity (ROA), have been emerged in the past decade as powerful spectroscopic tools for stereochemical information of a wide range of chiral compounds in solution directly. More recently, their applications in unveiling solvent effects, especially those associated with water solvent, have been explored. In this review article, we first select a few examples to demonstrate the unique sensitivity of VCD spectral signatures to both bulk solvent effects and explicit hydrogen-bonding interactions in solution. Second, we discuss the induced solvent chirality, or chiral transfer, VCD spectral features observed in the water bending band region in detail. From these chirality transfer spectral data, the related conformer specific gas phase spectroscopic studies of small chiral hydration clusters, and the associated matrix isolation VCD experiments of hydrogen-bonded complexes in cold rare gas matrices, a general picture of solvation in aqueous solution emerges. In such an aqueous solution, some small chiral hydration clusters, rather than the chiral solutes themselves, are the dominant species and are the ones that contribute mainly to the experimentally observed VCD features. We then review a series of VCD studies of amino acids and their derivatives in aqueous solution under different pHs to emphasize the importance of the inclusion of the bulk solvent effects. These experimental data and the associated theoretical analyses are the foundation for the proposed "clusters-in-a-liquid" approach to account for solvent effects effectively. We present several approaches to identify and build such representative chiral hydration clusters. Recent studies which applied molecular dynamics simulations and the subsequent snapshot averaging approach to generate the ROA, VCD, electronic CD, and optical rotatory dispersion spectra are also reviewed. Challenges associated with the molecular dynamics snapshot approach are discussed and the successes of the seemingly random "ad hoc explicit solvation" reported before are also explained. To further test and improve the "clusters-in-a-liquid" model in practice, future work in terms of conformer specific gas phase spectroscopy of sequential solvation of a chiral solute, matrix isolation VCD measurements of small chiral hydration clusters, and more sophisticated models for the bulk solvent effects would be highly valuable.
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Affiliation(s)
| | | | | | - Yunjie Xu
- Department of Chemistry, University of AlbertaEdmonton, AB, Canada
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12
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Induced circular dichroism of thioflavin T interacting with acetylcholinesterase: A computational study. Chem Phys 2015. [DOI: 10.1016/j.chemphys.2015.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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13
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Zhang SM, Zhang HY, Yang SX, Qu CL, Xie ZP, Pescitelli G. Isolation, Stereochemical Study, and Cytotoxic Activity of Isobenzofuran Derivatives From a MarineStreptomycessp. Chirality 2014; 27:82-7. [DOI: 10.1002/chir.22393] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 08/28/2014] [Accepted: 08/29/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Shu-Min Zhang
- School of Pharmaceutical Sciences; Binzhou Medical University; Yantai China
| | - Hong-Yu Zhang
- Tianjin Key Laboratory of Food Biotechnology, Department of Biological Technology and Food Science; Tianjin University of Commerce; Tianjin China
| | | | | | - Ze-Ping Xie
- School of Pharmaceutical Sciences; Binzhou Medical University; Yantai China
| | - Gennaro Pescitelli
- Dipartimento di Chimica e Chimica Industriale; Università di Pisa; Pisa Italy
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14
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Ruíz A, Morera-Boado C, Almagro L, Coro J, Maroto EE, Herranz MÁ, Filippone S, Molero D, Martínez-Álvarez R, Garcia de la Vega JM, Suárez M, Martín N. Dumbbell-Type Fullerene-Steroid Hybrids: A Join Experimental and Theoretical Investigation for Conformational, Configurational, and Circular Dichroism Assignments. J Org Chem 2014; 79:3473-86. [DOI: 10.1021/jo500178t] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
| | | | | | | | | | | | | | | | | | - José M. Garcia de la Vega
- Departamento de
Química Física Aplicada, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049-Madrid, Spain
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15
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Lu W, Du G, Liu K, Jiang L, Ling J, Shen Z. Chiroptical Inversion Induced by Rotation of a Carbon–Carbon Single Bond: An Experimental and Theoretical Study. J Phys Chem A 2013; 118:283-92. [DOI: 10.1021/jp410370q] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Wei Lu
- MOE Key
Laboratory of Macromolecular Synthesis and Functionalization, Department
of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Ganhong Du
- MOE Key
Laboratory of Macromolecular Synthesis and Functionalization, Department
of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Keyuan Liu
- MOE Key
Laboratory of Macromolecular Synthesis and Functionalization, Department
of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Liming Jiang
- MOE Key
Laboratory of Macromolecular Synthesis and Functionalization, Department
of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Jun Ling
- MOE Key
Laboratory of Macromolecular Synthesis and Functionalization, Department
of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
| | - Zhiquan Shen
- MOE Key
Laboratory of Macromolecular Synthesis and Functionalization, Department
of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China
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16
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Fleming AM, Orendt AM, He Y, Zhu J, Dukor RK, Burrows CJ. Reconciliation of chemical, enzymatic, spectroscopic and computational data to assign the absolute configuration of the DNA base lesion spiroiminodihydantoin. J Am Chem Soc 2013; 135:18191-204. [PMID: 24215588 DOI: 10.1021/ja409254z] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The diastereomeric spiroiminodihydantoin-2'-deoxyribonucleoside (dSp) lesions resulting from 2'-deoxyguanosine (dG) or 8-oxo-7,8-dihydro-2'-deoxyguanosine (dOG) oxidation have generated much attention due to their highly mutagenic nature. Their propeller-like shape leads these molecules to display mutational profiles in vivo that are stereochemically dependent. However, there exist conflicting absolute configuration assignments arising from electronic circular dichroism (ECD) and NOESY-NMR experiments; thus, providing definitive assignments of the 3D structure of these molecules is of great interest. In the present body of work, we present data inconsistent with the reported ECD assignments for the dSp diastereomers in the nucleoside context, in which the first eluting isomer from a Hypercarb HPLC column was assigned to be the S configuration, and the second was assigned the R configuration. The following experiments were conducted: (1) determination of the diastereomer ratio of dSp products upon one-electron oxidation of dG in chiral hybrid or propeller G-quadruplexes that expose the re or si face to solvent, respectively; (2) absolute configuration analysis using vibrational circular dichroism (VCD) spectroscopy; (3) reinterpretation of the ECD experimental spectra using time-dependent density functional theory (TDDFT) with the inclusion of 12 explicit H-bonding waters around the Sp free bases; and (4) reevaluation of calculated specific rotations for the Sp enantiomers using the hydration model in the TDDFT calculations. These new insights provide a fresh look at the absolute configuration assignments of the dSp diastereomers in which the first eluting from a Hypercarb-HPLC column is (-)-(R)-dSp and the second is (+)-(S)-dSp. These assignments now provide the basis for understanding the biological significance of the stereochemical dependence of enzymes that process this form of DNA damage.
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Affiliation(s)
- Aaron M Fleming
- Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112-0850, United States
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