1
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Rojas C, Sarmiento N, Ayora E, Pis Diez R. Computational prediction of retention times of veterinary antibiotics obtained by liquid chromatography-mass spectrometry. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2024; 104:6724-6732. [PMID: 38551410 DOI: 10.1002/jsfa.13499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 02/19/2024] [Accepted: 03/29/2024] [Indexed: 04/10/2024]
Abstract
BACKGROUND Veterinary antibiotics are chemical compounds used to kill or inhibit the growth of pathogenic bacteria associated with animal diseases. These molecules can be defined by their retention times (tR) in liquid chromatography-mass spectrometry (LC-MS). One strategy to predict the tR of new veterinary antibiotics is the development of predictive quantitative structure-property relationships (QSPRs), which were used in this study. RESULTS A database of 122 antibiotics was selected in which the tR was measured using a Hypersil GOLD column. An optimal three-feature model was developed by integrating the unsupervised variable reduction, replacement method variable subset selection, and multiple linear regression. The negligible differences among the coefficient of determination and the root-mean-square error for the training set (R2 = 0.902 and RMSEC = 0.871) and test set (Q2 = 0.854 and RMSEP = 1.064) indicate a stable and predictive model. In a further step, a more in-depth explanation of the mechanism of action of each descriptor in predicting the tR is provided, with the construction of the theoretical chemical space for accurate predictions of new antibiotics. CONCLUSION The in silico model developed in this work identified three molecular descriptors associated with aqueous solubility, octanol-water partition coefficient, and the presence of negative and lipophilic atom pairs. The QSPR developed here could be implemented by agricultural and food chemists to identify and monitor existing and new antibiotics within the framework of LC-MS. The computational model was developed in accordance with five principles outlined by the Organization for Economic Co-operation and Development. © 2024 Society of Chemical Industry.
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Affiliation(s)
- Cristian Rojas
- Grupo de Investigación en Quimiometría y QSAR, Facultad de Ciencia y Tecnología, Universidad del Azuay, Cuenca, Ecuador
| | - Nicole Sarmiento
- Grupo de Investigación en Quimiometría y QSAR, Facultad de Ciencia y Tecnología, Universidad del Azuay, Cuenca, Ecuador
| | - Emilia Ayora
- Grupo de Investigación en Quimiometría y QSAR, Facultad de Ciencia y Tecnología, Universidad del Azuay, Cuenca, Ecuador
| | - Reinaldo Pis Diez
- CEQUINOR, Centro de Química Inorgánica (CONICET, UNLP), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), La Plata, Argentina
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2
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Hecht H, Rojas WY, Ahmad Z, Křenek A, Klánová J, Price EJ. Quantum Chemistry-Based Prediction of Electron Ionization Mass Spectra for Environmental Chemicals. Anal Chem 2024; 96:13652-13662. [PMID: 39110763 DOI: 10.1021/acs.analchem.4c02589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
There is a lack of experimental electron ionization high-resolution mass spectra available to assist compound identification. The in silico generation of mass spectra by quantum chemistry can aid annotation workflows, in particular to support the identification of compounds that lack experimental reference spectra, such as environmental chemicals. We present an open-source, semiautomated workflow for the in silico prediction of electron ionization high-resolution mass spectra at 70 eV based on the QCxMS software. The workflow was applied to predict the spectra of 367 environmental chemicals, and the accuracy was evaluated by comparison to experimental reference spectra acquired. The molecular flexibility, number of rotatable bonds, and number of electronegative atoms of a compound were negatively correlated with prediction accuracy. Few analytes are predicted to sufficient accuracy for the direct application of predicted spectra in spectral matching workflows (overall average score 428). The m/z values of the top 5 most abundant ions of predicted spectra rarely match ions in experimental spectra, evidencing the disconnect between simulated fragmentation pathways and empirical reaction mechanisms.
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Affiliation(s)
- Helge Hecht
- RECETOX, Faculty of Science, Masaryk University, Kotlářská 2, Brno 602 00, Czech Republic
| | - Wudmir Y Rojas
- RECETOX, Faculty of Science, Masaryk University, Kotlářská 2, Brno 602 00, Czech Republic
| | - Zargham Ahmad
- RECETOX, Faculty of Science, Masaryk University, Kotlářská 2, Brno 602 00, Czech Republic
| | - Aleš Křenek
- Institute of Computer Science, Masaryk University, Botanická 554/68a, Brno 602 00, Czech Republic
| | - Jana Klánová
- RECETOX, Faculty of Science, Masaryk University, Kotlářská 2, Brno 602 00, Czech Republic
| | - Elliott J Price
- RECETOX, Faculty of Science, Masaryk University, Kotlářská 2, Brno 602 00, Czech Republic
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3
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Friede M, Hölzer C, Ehlert S, Grimme S. dxtb-An efficient and fully differentiable framework for extended tight-binding. J Chem Phys 2024; 161:062501. [PMID: 39120026 DOI: 10.1063/5.0216715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Accepted: 07/18/2024] [Indexed: 08/10/2024] Open
Abstract
Automatic differentiation (AD) emerged as an integral part of machine learning, accelerating model development by enabling gradient-based optimization without explicit analytical derivatives. Recently, the benefits of AD and computing arbitrary-order derivatives with respect to any variable were also recognized in the field of quantum chemistry. In this work, we present dxtb-an open-source, fully differentiable framework for semiempirical extended tight-binding (xTB) methods. Developed entirely in Python and leveraging PyTorch for array operations, dxtb facilitates extensibility and rapid prototyping while maintaining computational efficiency. Through comprehensive code vectorization and optimization, we essentially reach the speed of compiled xTB programs for high-throughput calculations of small molecules. The excellent performance also scales to large systems, and batch operability yields additional benefits for execution on parallel hardware. In particular, energy evaluations are on par with existing programs, whereas the speed of automatically differentiated nuclear derivatives is only 2 to 5 times slower compared to their analytical counterparts. We showcase the utility of AD in dxtb by calculating various molecular and spectroscopic properties, highlighting its capacity to enhance and simplify such evaluations. Furthermore, the framework streamlines optimization tasks and offers seamless integration of semiempirical quantum chemistry in machine learning, paving the way for physics-inspired end-to-end differentiable models. Ultimately, dxtb aims to further advance the capabilities of semiempirical methods, providing an extensible foundation for future developments and hybrid machine learning applications. The framework is accessible at https://github.com/grimme-lab/dxtb.
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Affiliation(s)
- Marvin Friede
- Mulliken Center for Theoretical Chemistry, University of Bonn, Bonn 53115, Germany
| | - Christian Hölzer
- Mulliken Center for Theoretical Chemistry, University of Bonn, Bonn 53115, Germany
| | - Sebastian Ehlert
- AI4Science, Microsoft Research, Evert van de Beekstraat 354, 1118CZ Schiphol, Netherlands
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, University of Bonn, Bonn 53115, Germany
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4
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Dantus M. Ultrafast studies of elusive chemical reactions in the gas phase. Science 2024; 385:eadk1833. [PMID: 39116221 DOI: 10.1126/science.adk1833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Accepted: 06/11/2024] [Indexed: 08/10/2024]
Abstract
The chemical composition of the interstellar medium and planetary atmospheres is constantly in flux as atoms and molecules collide and interact with high-energy particles such as electrons, protons, and photons. These transformative processes ultimately lead to the coalescence of molecules and eventually the birth of stars. Our understanding of these chemical ecosystems relies on models that synthesize data from gas-phase experiments, providing insights into reaction cross sections. This Review examines efforts to delve into the fundamental bond-forming and bond-breaking dynamics that occur during bimolecular and electron-initiated reactions. These experiments involve clever approaches to establish a time reference and the collision geometry necessary for tracking atomic motion with femtosecond time resolution. Findings from these efforts enhance present models and improve predictions for molecule-molecule and electron-molecule collisions.
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Affiliation(s)
- Marcos Dantus
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
- Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
- Department of Electrical and Computer Engineering, Michigan State University, East Lansing, MI 48824, USA
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5
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Balzaretti F, Voss J. Density Functional Tight-Binding Models for Band Structures of Transition-Metal Alloys and Surfaces across the d-Block. J Chem Theory Comput 2024. [PMID: 39118401 DOI: 10.1021/acs.jctc.4c00345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
First-principles electronic structure simulations are an invaluable tool for understanding chemical bonding and reactions. While machine-learning models such as interatomic potentials significantly accelerate the exploration of potential energy surfaces, electronic structure information is generally lost. Particularly in the field of heterogeneous catalysis, simulated electron band structures provide fundamental insights into catalytic reactivity. This ab initio knowledge is preserved in semiempirical methods such as density functional tight binding (DFTB), which extend the accessible computational length and time scales beyond first-principles approaches. In this paper we present Shell-Optimized Atomic Confinement (SOAC) DFTB electronic-part-only parametrizations for bulk and surface band structures of all d-block transition metals that enable efficient predictions of electronic descriptors for large structures or high-throughput studies on complex systems outside the computational reach of density functional theory.
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Affiliation(s)
- Filippo Balzaretti
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States
| | - Johannes Voss
- SUNCAT Center for Interface Science and Catalysis, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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6
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Metz TO, Chang CH, Gautam V, Anjum A, Tian S, Wang F, Colby SM, Nunez JR, Blumer MR, Edison AS, Fiehn O, Jones DP, Li S, Morgan ET, Patti GJ, Ross DH, Shapiro MR, Williams AJ, Wishart DS. Introducing 'identification probability' for automated and transferable assessment of metabolite identification confidence in metabolomics and related studies. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.30.605945. [PMID: 39131324 PMCID: PMC11312557 DOI: 10.1101/2024.07.30.605945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
Methods for assessing compound identification confidence in metabolomics and related studies have been debated and actively researched for the past two decades. The earliest effort in 2007 focused primarily on mass spectrometry and nuclear magnetic resonance spectroscopy and resulted in four recommended levels of metabolite identification confidence - the Metabolite Standards Initiative (MSI) Levels. In 2014, the original MSI Levels were expanded to five levels (including two sublevels) to facilitate communication of compound identification confidence in high resolution mass spectrometry studies. Further refinement in identification levels have occurred, for example to accommodate use of ion mobility spectrometry in metabolomics workflows, and alternate approaches to communicate compound identification confidence also have been developed based on identification points schema. However, neither qualitative levels of identification confidence nor quantitative scoring systems address the degree of ambiguity in compound identifications in context of the chemical space being considered, are easily automated, or are transferable between analytical platforms. In this perspective, we propose that the metabolomics and related communities consider identification probability as an approach for automated and transferable assessment of compound identification and ambiguity in metabolomics and related studies. Identification probability is defined simply as 1/N, where N is the number of compounds in a reference library or chemical space that match to an experimentally measured molecule within user-defined measurement precision(s), for example mass measurement or retention time accuracy, etc. We demonstrate the utility of identification probability in an in silico analysis of multi-property reference libraries constructed from the Human Metabolome Database and computational property predictions, provide guidance to the community in transparent implementation of the concept, and invite the community to further evaluate this concept in parallel with their current preferred methods for assessing metabolite identification confidence.
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Affiliation(s)
- Thomas O. Metz
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA USA
| | - Christine H. Chang
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA USA
| | - Vasuk Gautam
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Afia Anjum
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Siyang Tian
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Fei Wang
- Department of Computing Science, University of Alberta, Edmonton, AB, Canada
- Alberta Machine Intelligence Institute, Edmonton, AB, Canada
| | - Sean M. Colby
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA USA
| | - Jamie R. Nunez
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA USA
| | - Madison R. Blumer
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA USA
| | - Arthur S. Edison
- Department of Biochemistry & Molecular Biology, Complex Carbohydrate Research Center and Institute of Bioinformatics, University of Georgia, Athens, GA, USA
| | - Oliver Fiehn
- West Coast Metabolomics Center, University of California Davis, Davis, CA, USA
| | - Dean P. Jones
- Clinical Biomarkers Laboratory, Department of Medicine, Emory University, Atlanta, Georgia, USA
| | - Shuzhao Li
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA
| | - Edward T. Morgan
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Gary J. Patti
- Center for Mass Spectrometry and Metabolic Tracing, Department of Chemistry, Department of Medicine, Washington University, Saint Louis, Missouri, USA
| | - Dylan H. Ross
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA USA
| | - Madelyn R. Shapiro
- Artificial Intelligence & Data Analytics Division, Pacific Northwest National Laboratory, Richland, WA USA
| | - Antony J. Williams
- U.S. Environmental Protection Agency, Office of Research & Development, Center for Computational Toxicology & Exposure (CCTE), Research Triangle Park, NC USA
| | - David S. Wishart
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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7
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Cui M, Reuter K, Margraf JT. Obtaining Robust Density Functional Tight-Binding Parameters for Solids across the Periodic Table. J Chem Theory Comput 2024; 20:5276-5290. [PMID: 38865478 DOI: 10.1021/acs.jctc.4c00228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
The density functional tight-binding (DFTB) approach allows electronic structure-based simulations at length and time scales far beyond what is possible with first-principles methods. This is achieved by using minimal basis sets and empirical approximations. Unfortunately, the sparse availability of parameters across the periodic table is a significant barrier to the use of DFTB in many cases. We therefore propose a workflow that allows the robust and consistent parametrization of DFTB across the periodic table. Importantly, our approach requires no element-pairwise parameters so that the parameters can be used for all element combinations and are readily extendable. This is achieved by parametrizing all elements on a consistent set of artificial homoelemental crystals, spanning a wide range of coordination environments. The transferability of the resulting periodic table baseline parameters to multielement systems and unknown structures is explored and the model is extensively benchmarked against previous specialized and general DFTB parametrizations.
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Affiliation(s)
- Mengnan Cui
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
- University of Bayreuth, Bavarian Center for Battery Technology (BayBatt), 95448 Bayreuth, Germany
| | - Karsten Reuter
- Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - Johannes T Margraf
- University of Bayreuth, Bavarian Center for Battery Technology (BayBatt), 95448 Bayreuth, Germany
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8
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Liu T, Chen L, Wang X, Cooper AI. Screening potential dye sensitizers for water splitting photocatalysts using a genetic algorithm. Phys Chem Chem Phys 2024; 26:16847-16858. [PMID: 38832434 DOI: 10.1039/d4cp01487a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
Addressing the global fossil energy crisis necessitates the efficient utilization of sustainable energy sources. Hydrogen, a green fuel, can be generated using sunlight, water, and a photocatalyst. Employing sensitizers holds promise for enhancing photocatalyst performance, enabling high rates of hydrogen evolution through increased visible light absorption. However, sifting through millions of diverse molecules to identify suitable dyes for specific photocatalysts poses a significant challenge. In this study, we integrate genetic algorithm and geometry-frequency-noncovalent extended tight binding methods to efficiently screen 2.6 million potential sensitizers with a D-π-A-π-AA structure within a short timeframe. Subsequently, these optimized sensitizers are rigorously reassessed by using DFT/TDDFT methods, elucidating why they may serve as superior dyes compared to the reference dye WS5F, particularly in terms of light absorption, driving force, binding energy, etc. Additionally, our methodology uncovers molecular motifs of particular interest, including the furan π-bridge and the double cyano anchoring acceptor, which are prevalent in the most promising set of molecules. The developed genetic algorithm workflow and dye design principles can be extended to various compelling projects, such as dye-sensitized solar cells, organic photovoltaics, photo-induced redox reactions, pharmaceuticals, and beyond.
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Affiliation(s)
- Tao Liu
- Department of Chemistry and Materials Innovation Factory, Leverhulme Research Centre for Functional Materials Design, University of Liverpool, 51 Oxford Street, Liverpool, L7 3NY, UK.
| | - Linjiang Chen
- School of Chemistry and School of Computer Science, University of Birmingham, Birmingham, B15 2TT, UK.
| | - Xiaoyan Wang
- Department of Chemistry and Materials Innovation Factory, Leverhulme Research Centre for Functional Materials Design, University of Liverpool, 51 Oxford Street, Liverpool, L7 3NY, UK.
| | - Andrew I Cooper
- Department of Chemistry and Materials Innovation Factory, Leverhulme Research Centre for Functional Materials Design, University of Liverpool, 51 Oxford Street, Liverpool, L7 3NY, UK.
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9
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Dantus M. Tracking Molecular Fragmentation in Electron-Ionization Mass Spectrometry with Ultrafast Time Resolution. Acc Chem Res 2024; 57:845-854. [PMID: 38366970 PMCID: PMC10956387 DOI: 10.1021/acs.accounts.3c00713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Revised: 01/24/2024] [Accepted: 01/26/2024] [Indexed: 02/19/2024]
Abstract
ConspectusMass spectrometry is a powerful analytical method capable of identifying compounds given a minute amount of material. The fragmentation pattern that results following molecular activation serves as a fingerprint that can be matched to a database compound for identification. Over the past half century, studies have addressed and, in many cases, named the chemical reactions that lead to some of the principal fragment ions. Theories have been developed to predict the observed fragmentation patterns, many of which assume that energy redistributes prior to dissociation. However, the existence of rearrangements and nonergodic processes complicates the prediction of fragmentation patterns and the identification of compounds that have yet to be entered into a curated database. To date, very few studies have addressed the time-dependent nature of the fragmentation of radical cations and, in particular, processes occurring with picosecond or shorter time scales where one expects to find nonergodic reactions.This Account focuses on a novel approach that enables tracking of molecular fragmentation in electron-ionization mass spectrometry with ultrafast time resolution. The two challenges that have prevented the time-resolved studies following electron ionization are the random impact parameter and moment of ionization of each molecule. In addition, medium-sized molecules can produce fragmentation patterns with tens if not hundreds of product ions. Spectroscopically interrogating all of these ions as a function of time is another major challenge. We describe strong field disruptive probing, a method that ionizes molecules on a femtosecond time scale and allows us to track in time the formation of all fragment ions simultaneously.Molecular fragmentation following ionization can occur on a very wide range of time scales. Metastable ions can survive from nanoseconds to microseconds; reactions that depend on vibrational energy redistribution can take picoseconds to nanoseconds; and direct dissociation processes and some rearrangements can take place in femtoseconds to picoseconds. All of these processes depend on the dynamics that occur during attoseconds and femtoseconds following the ionization process. Following a discussion of these time scales, we provide three examples of fragmentations that have been studied with femtosecond time resolution. Each of these examples include unforeseen reaction dynamics that involve a nonergodic process, highlighting the importance of time resolution in mass spectrometry. Finally, we explore future challenges and unresolved questions in mass spectrometry and, more broadly, in the domain of electron-initiated chemical reactions.
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Affiliation(s)
- Marcos Dantus
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
- Department
of Physics and Astronomy, Michigan State
University, East Lansing, Michigan 48824, United States
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10
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Park J, Jo J, Yoon S. Mass spectra prediction with structural motif-based graph neural networks. Sci Rep 2024; 14:1400. [PMID: 38228685 PMCID: PMC10792027 DOI: 10.1038/s41598-024-51760-x] [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: 09/18/2023] [Accepted: 01/09/2024] [Indexed: 01/18/2024] Open
Abstract
Mass spectra, which are agglomerations of ionized fragments from targeted molecules, play a crucial role across various fields for the identification of molecular structures. A prevalent analysis method involves spectral library searches, where unknown spectra are cross-referenced with a database. The effectiveness of such search-based approaches, however, is restricted by the scope of the existing mass spectra database, underscoring the need to expand the database via mass spectra prediction. In this research, we propose the Motif-based Mass Spectrum prediction Network (MoMS-Net), a GNN-based architecture to predict the mass spectra pattern utilizing the structural motif information of the molecule. MoMS-Net considers both a molecule and its substructures as a graph form, which facilitates the incorporation of long-range dependencies while using less memory compared to the graph transformer model. We evaluated our model over various types of mass spectra and showed the validity and superiority over the conventional models.
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Affiliation(s)
- Jiwon Park
- Interdisciplinary Program in Artificial Intelligence, Seoul National University, Seoul, 08826, Republic of Korea
- LG Chem, Seoul, 07795, Republic of Korea
| | - Jeonghee Jo
- Center for Neuromorphic Engineering, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea.
| | - Sungroh Yoon
- Interdisciplinary Program in Artificial Intelligence, Seoul National University, Seoul, 08826, Republic of Korea.
- Department of Electrical and Computer Engineering, Seoul National University, Seoul, 08826, Republic of Korea.
- Artificial Intelligence Institute, Seoul National University, Seoul, 08826, Republic of Korea.
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11
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Vink MA, Alarcan J, Martens J, Buma WJ, Braeuning A, Berden G, Oomens J. Structural Elucidation of Agrochemical Metabolic Transformation Products Based on Infrared Ion Spectroscopy to Improve In Silico Toxicity Assessment. Chem Res Toxicol 2024; 37:81-97. [PMID: 38118149 PMCID: PMC10792670 DOI: 10.1021/acs.chemrestox.3c00316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2023] [Revised: 12/03/2023] [Accepted: 12/05/2023] [Indexed: 12/22/2023]
Abstract
Toxicological assessments of newly developed agrochemical agents consider chemical modifications and their metabolic and biotransformation products. To carry out an in silico hazard assessment, understanding the type of chemical modification and its location on the original compound can greatly enhance the reliability of the evaluation. Here, we present and apply a method based on liquid chromatography-mass spectrometry (LC-MS) enhanced with infrared ion spectroscopy (IRIS) to better delineate the molecular structures of transformation products before in silico toxicology evaluation. IRIS facilitates the recording of IR spectra directly in the mass spectrometer for features selected by retention time and mass-to-charge ratio. By utilizing quantum-chemically predicted IR spectra for candidate molecular structures, one can either derive the actual structure or significantly reduce the number of (isomeric) candidate structures. This approach can assist in making informed decisions. We apply this method to a plant growth stimulant, digeraniol sinapoyl malate (DGSM), that is currently under development. Incubation of the compound in Caco-2 and HepaRG cell lines in multiwell plates and analysis by LC-MS reveals oxidation, glucuronidation, and sulfonation metabolic products, whose structures were elucidated by IRIS and used as input for an in silico toxicology assessment. The toxicity of isomeric metabolites predicted by in silico tools was also assessed, which revealed that assigning the right metabolite structure is an important step in the overall toxicity assessment of the agrochemical. We believe this identification approach can be advantageous when specific isomers are significantly more hazardous than others and can help better understand metabolic pathways.
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Affiliation(s)
- Matthias
J. A. Vink
- Institute
for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Jimmy Alarcan
- Department
of Food Safety, German Federal Institute
for Risk Assessment, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Jonathan Martens
- Institute
for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Wybren Jan Buma
- Institute
for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
- van’t
Hoff Institute for Molecular Sciences, University
of Amsterdam, Science
Park 904, 1098 XH Amsterdam, The Netherlands
| | - Albert Braeuning
- Department
of Food Safety, German Federal Institute
for Risk Assessment, Max-Dohrn-Str. 8-10, 10589 Berlin, Germany
| | - Giel Berden
- Institute
for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
| | - Jos Oomens
- Institute
for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, 6525 ED Nijmegen, The Netherlands
- van’t
Hoff Institute for Molecular Sciences, University
of Amsterdam, Science
Park 904, 1098 XH Amsterdam, The Netherlands
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12
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Li T, Su W, Zhong L, Liang W, Feng X, Zhu B, Ruan T, Jiang G. An Integrated Workflow Assisted by In Silico Predictions To Expand the List of Priority Polycyclic Aromatic Compounds. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:20854-20863. [PMID: 38010983 DOI: 10.1021/acs.est.3c07087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The limited information in existing mass spectral libraries hinders an accurate understanding of the composition, behavior, and toxicity of organic pollutants. In this study, a total of 350 polycyclic aromatic compounds (PACs) in 9 categories were successfully identified in fine particulate matter by gas chromatography high resolution mass spectrometry. Using mass spectra and retention indexes predicted by in silico tools as complementary information, the scope of chemical identification was efficiently expanded by 27%. In addition, quantitative structure-activity relationship models provided toxicity data for over 70% of PACs, facilitating a comprehensive health risk assessment. On the basis of extensive identification, the cumulative noncarcinogenic risk of PACs warranted attention. Meanwhile, the carcinogenic risk of 53 individual analogues was noteworthy. These findings suggest that there is a pressing need for an updated list of priority PACs for routine monitoring and toxicological research since legacy polycyclic aromatic hydrocarbons (PAHs) contributed modestly to the overall abundance (18%) and carcinogenic risk (8%). A toxicological priority index approach was applied for relative chemical ranking considering the environmental occurrence, fate, toxicity, and analytical availability. A list of 39 priority analogues was compiled, which predominantly consisted of high-molecular-weight PAHs and alkyl derivatives. These priority PACs further enhanced source interpretation, and the highest carcinogenic risk was attributed to coal combustion.
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Affiliation(s)
- Tingyu Li
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenyuan Su
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Laijin Zhong
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenqing Liang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoxia Feng
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bao Zhu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ting Ruan
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guibin Jiang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
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13
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Takayama M, Ubukata M, Nagatomo K, Tamura J, Kubota A. Quantum Chemical Analysis of Molecular and Fragment Ions Produced by Field Ionization of Methyl Stearate. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:2731-2738. [PMID: 37902792 DOI: 10.1021/jasms.3c00277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
The formation of molecular and fragment ions observed in the field ionization mass spectrum of methyl stearate has been analyzed on the basis of quantum chemical calculations including time-dependent density functional theory (TDDFT) and natural bond orbital (NBO) analysis. The TDDFT calculations suggest that methyl stearate is ionized via two processes, namely a 7.43 eV excitation and a tunneling effect, while the high electric field of 1010 V/m enables analyte molecules to ionize at an effective 6 eV lower than the 9.26 eV ionization energy. The NBO analysis suggests that the abundances of aliphatic fragment ions [CnH2n+1]+ at m/z 29, 43, and 57 generated in the ionizing cell can be rationalized by hyperconjugation between the sigma (σ)-electrons of sp3 C-H bonds of methyl or methylene groups and the empty p-orbital of the carbocation -CH2+. The C4 periodic methyl ester fragment ions at m/z 115-269 and the complementary McLafferty rearrangement fragment ion at m/z 224 can be explained by metastable ion decay with rearrangement reactions in the ion source.
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Affiliation(s)
- Mitsuo Takayama
- Graduate School in Nanobioscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Yokohama 236-0027, Japan
| | | | | | - Jun Tamura
- JEOL Ltd., Akishima, Tokyo 196-8558, Japan
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14
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Devata S, Cleaves HJ, Dimandja J, Heist CA, Meringer M. Comparative Evaluation of Electron Ionization Mass Spectral Prediction Methods. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023. [PMID: 37390315 DOI: 10.1021/jasms.3c00059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/02/2023]
Abstract
During the past decade promising methods for computational prediction of electron ionization mass spectra have been developed. The most prominent ones are based on quantum chemistry (QCEIMS) and machine learning (CFM-EI, NEIMS). Here we provide a threefold comparison of these methods with respect to spectral prediction and compound identification. We found that there is no unambiguous way to determine the best of these three methods. Among other factors, we find that the choice of spectral distance functions play an important role regarding the performance for compound identification.
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Affiliation(s)
- Sriram Devata
- International Institute of Information Technology, Hyderabad 500 032, India
- Blue Marble Space Institute of Science, 1001 4th Ave, Suite 3201, Seattle, Washington 98154, United States
| | - Henderson James Cleaves
- Blue Marble Space Institute of Science, 1001 4th Ave, Suite 3201, Seattle, Washington 98154, United States
- Earth-Life Science Institute, Tokyo Institute of Technology, 2-12-1-IE-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - John Dimandja
- Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Christopher A Heist
- Georgia Tech Research Institute (GTRI), Georgia Institute of Technology, Atlanta, Georgia 30332, United States
| | - Markus Meringer
- Department of Atmospheric Processors, German Aerospace Center (DLR), Münchner Straße 20, 82234 Oberpfaffenhofen-Wessling, Germany
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15
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Zhang B, Hao M, Xiong J, Li X, Koopman J. Ab initio molecular dynamics calculations on electron ionization induced fragmentations of C 4F 7N and C 5F 10O for understanding their decompositions under discharge conditions. Phys Chem Chem Phys 2023; 25:7540-7549. [PMID: 36857631 DOI: 10.1039/d2cp03498k] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
C4F7N and C5F10O are the most promising SF6 alternatives as eco-friendly insulating gaseous mediums in electrical engineering. It is necessary to clarify their electrical stability and decomposition mechanisms. In this work, we first introduced our experimental results for decomposition products of C4F7N/CO2 and C5F10O/synthetic air mixtures under partial discharge and spark discharge conditions. Then, we performed ab initio molecular dynamics (AIMD) simulations on the typical decomposition products. The simulations were performed under standard electron impact mass spectrometry (EI-MS); thus, the statistical results of the mass spectra were compared with those of the experimentally obtained standard mass spectra from the NIST database. The AIMD simulation method in simulating the electron-induced ionization process was verified and found to be reliable. Finally, the calculations were also performed for C4F7N and C5F10O with incident electron energies of 20 eV and 70 eV, respectively. The dominant pathway for both gases is the formation of CF3+ with the fracture of the C-C bond. The AIMD simulation is able to predict the decomposition channels after electron-impact ionization without any preconceived knowledge of fragmentation pathways, which provides a novel insight into understanding the decomposition mechanisms of C4F7N and C5F10O under different discharge conditions with different energies.
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Affiliation(s)
- Boya Zhang
- State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China.
| | - Mai Hao
- State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China.
| | - Jiayu Xiong
- State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China. .,State Grid Sichuan Electric Power Research Institute, Chengdu, Sichuan Province 610041, China
| | - Xingwen Li
- State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China.
| | - Jeroen Koopman
- Mulliken Center for Theoretical Chemistry, Institute of Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
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16
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Terrones GG, Duan C, Nandy A, Kulik HJ. Low-cost machine learning prediction of excited state properties of iridium-centered phosphors. Chem Sci 2023; 14:1419-1433. [PMID: 36794185 PMCID: PMC9906783 DOI: 10.1039/d2sc06150c] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 01/05/2023] [Indexed: 01/07/2023] Open
Abstract
Prediction of the excited state properties of photoactive iridium complexes challenges ab initio methods such as time-dependent density functional theory (TDDFT) both from the perspective of accuracy and of computational cost, complicating high-throughput virtual screening (HTVS). We instead leverage low-cost machine learning (ML) models and experimental data for 1380 iridium complexes to perform these prediction tasks. We find the best-performing and most transferable models to be those trained on electronic structure features from low-cost density functional tight binding calculations. Using artificial neural network (ANN) models, we predict the mean emission energy of phosphorescence, the excited state lifetime, and the emission spectral integral for iridium complexes with accuracy competitive with or superseding that of TDDFT. We conduct feature importance analysis to determine that high cyclometalating ligand ionization potential correlates to high mean emission energy, while high ancillary ligand ionization potential correlates to low lifetime and low spectral integral. As a demonstration of how our ML models can be used for HTVS and the acceleration of chemical discovery, we curate a set of novel hypothetical iridium complexes and use uncertainty-controlled predictions to identify promising ligands for the design of new phosphors while retaining confidence in the quality of the ANN predictions.
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Affiliation(s)
- Gianmarco G. Terrones
- Department of Chemical Engineering, Massachusetts Institute of TechnologyCambridgeMA 02139USA
| | - Chenru Duan
- Department of Chemical Engineering, Massachusetts Institute of TechnologyCambridgeMA 02139USA,Department of Chemistry, Massachusetts Institute of TechnologyCambridgeMA 02139USA
| | - Aditya Nandy
- Department of Chemical Engineering, Massachusetts Institute of TechnologyCambridgeMA 02139USA,Department of Chemistry, Massachusetts Institute of TechnologyCambridgeMA 02139USA
| | - Heather J. Kulik
- Department of Chemical Engineering, Massachusetts Institute of TechnologyCambridgeMA 02139USA,Department of Chemistry, Massachusetts Institute of TechnologyCambridgeMA 02139USA
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17
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Koopman J, Grimme S. Calculation of Mass Spectra with the QCxMS Method for Negatively and Multiply Charged Molecules. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:2226-2242. [PMID: 36343304 DOI: 10.1021/jasms.2c00209] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Analysis and validation of a mass spectrometry (MS) experiment are usually performed by comparison to reference spectra. However, if references are missing, measured spectra cannot be properly matched. To close this gap, the Quantum Chemical Mass Spectrometry (QCxMS) program has been developed. It enables fully automatic calculations of electron ionization (EI) and positive ion collision-induced dissociation (CID) mass spectra of singly charged molecular ions. In this work, the extension to negative and multiple ion charge for the CID run mode is presented. QCxMS is now capable of calculating structures carrying any charge, without the need for pretabulated fragmentation pathways or machine learning of database spectra. Mass spectra of four single negatively charged and two multiple positively charged organic ions with molecular sizes from 12 to 92 atoms were computed and compared to reference spectra. The underlying Born-Oppenheimer molecular dynamics (MD) calculations were conducted using the semiempirical quantum mechanical GFN2-xTB method, while for some small molecules, ab initio DFT-based MD simulations were performed. Detailed insights into the fragmentation pathways were gained, and the effects of the computed charge assignments on the resulting spectrum are discussed. Especially for the negative ion mode, the influence of the deprotonation site to create the anion was found to be substantial. Doubly charged fragments could successfully be calculated fully automatically for the first time, while higher charged structures introduced severe assignment problems. Overall, this extension of the QCxMS program further enhances its applicability and underlines its value as a sophisticated toolkit for CID-based tandem MS structure elucidation.
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Affiliation(s)
- Jeroen Koopman
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115Bonn, Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115Bonn, Germany
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18
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Vink M, van Geenen FA, Berden G, O’Riordan TJC, Howe PW, Oomens J, Perry SJ, Martens J. Structural Elucidation of Agrochemicals and Related Derivatives Using Infrared Ion Spectroscopy. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:15563-15572. [PMID: 36214158 PMCID: PMC9671053 DOI: 10.1021/acs.est.2c03210] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 09/15/2022] [Accepted: 09/19/2022] [Indexed: 06/03/2023]
Abstract
Agrochemicals frequently undergo various chemical and metabolic transformation reactions in the environment that often result in a wide range of derivates that must be comprehensively characterized to understand their toxicity profiles and their persistence and outcome in the environment. In the development phase, this typically involves a major effort in qualitatively identifying the correct chemical isomer(s) of these derivatives from the many isomers that could potentially be formed. Liquid chromatography-mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy are often used in attempts to characterize such environment transformation products. However, challenges in confidently correlating chemical structures to detected compounds in mass spectrometry data and sensitivity/selectivity limitations of NMR frequently lead to bottlenecks in identification. In this study, we use an alternative approach, infrared ion spectroscopy, to demonstrate the identification of hydroxylated derivatives of two plant protection compounds (azoxystrobin and benzovindiflupyr) contained at low levels in tomato and spinach matrices. Infrared ion spectroscopy is an orthogonal tandem mass spectrometry technique that combines the sensitivity and selectivity of mass spectrometry with structural information obtained by infrared spectroscopy. Furthermore, IR spectra can be computationally predicted for candidate molecular structures, enabling the tentative identification of agrochemical derivatives and other unknowns in the environment without using physical reference standards.
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Affiliation(s)
- Matthias
J.A. Vink
- FELIX
Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525ED Nijmegen, the Netherlands
| | - Fred A.M.G. van Geenen
- FELIX
Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525ED Nijmegen, the Netherlands
| | - Giel Berden
- FELIX
Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525ED Nijmegen, the Netherlands
| | - Timothy J. C. O’Riordan
- Syngenta,
Jealott’s Hill International Research Centre, RG42 6EY, Bracknell, Berkshire, United Kingdom
| | - Peter W.A. Howe
- Syngenta,
Jealott’s Hill International Research Centre, RG42 6EY, Bracknell, Berkshire, United Kingdom
| | - Jos Oomens
- FELIX
Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525ED Nijmegen, the Netherlands
| | - Simon J. Perry
- Syngenta,
Jealott’s Hill International Research Centre, RG42 6EY, Bracknell, Berkshire, United Kingdom
| | - Jonathan Martens
- FELIX
Laboratory, Institute for Molecules and Materials, Radboud University, Toernooiveld 7, 6525ED Nijmegen, the Netherlands
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19
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Wang S, Kind T, Bremer PL, Tantillo DJ, Fiehn O. Beyond the Ground State: Predicting Electron Ionization Mass Spectra Using Excited-State Molecular Dynamics. J Chem Inf Model 2022; 62:4403-4410. [DOI: 10.1021/acs.jcim.2c00597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shunyang Wang
- West Coast Metabolomics Center, UC Davis Genome Center, University of California, 451 Health Sciences Drive, Davis, California 95616, United States
- Department of Chemistry, University of California, 1 Shields Avenue, Davis, California 95616, United States
| | - Tobias Kind
- West Coast Metabolomics Center, UC Davis Genome Center, University of California, 451 Health Sciences Drive, Davis, California 95616, United States
| | - Parker Ladd Bremer
- West Coast Metabolomics Center, UC Davis Genome Center, University of California, 451 Health Sciences Drive, Davis, California 95616, United States
- Department of Chemistry, University of California, 1 Shields Avenue, Davis, California 95616, United States
| | - Dean J. Tantillo
- Department of Chemistry, University of California, 1 Shields Avenue, Davis, California 95616, United States
| | - Oliver Fiehn
- West Coast Metabolomics Center, UC Davis Genome Center, University of California, 451 Health Sciences Drive, Davis, California 95616, United States
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20
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Bremer PL, Vaniya A, Kind T, Wang S, Fiehn O. How Well Can We Predict Mass Spectra from Structures? Benchmarking Competitive Fragmentation Modeling for Metabolite Identification on Untrained Tandem Mass Spectra. J Chem Inf Model 2022; 62:4049-4056. [PMID: 36043939 DOI: 10.1021/acs.jcim.2c00936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Competitive Fragmentation Modeling for Metabolite Identification (CFM-ID) is a machine learning tool to predict in silico tandem mass spectra (MS/MS) for known or suspected metabolites for which chemical reference standards are not available. As a machine learning tool, it relies on both an underlying statistical model and an explicit training set that encompasses experimental mass spectra for specific compounds. Such mass spectra depend on specific parameters such as collision energies, instrument types, and adducts which are accumulated in libraries. Yet, ultimately prediction tools that are meant to cover wide expanses of entities must be validated on cases that were not included in the initial training and testing sets. Hence, we here benchmarked the performance of CFM-ID 4.0 to correctly predict MS/MS spectra for spectra that were not included in the CFM-ID training set and for different mass spectrometry conditions. We used 609,456 experimental tandem spectra from the NIST20 mass spectral library that were newly added to the previous NIST17 library version. We found that CFM-ID's highest energy prediction output would maximize the capacity for library generation. Matching the experimental collision energy with CFM-ID's prediction energy produced the best results, even for HCD-Orbitrap instruments. For benzenoids, better MS/MS predictions were achieved than for heterocyclic compounds. However, when exploring CFM-ID's performance on 8,305 compounds at 40 eV HCD-Orbitrap collision energy, >90% of the 20/80 split test compounds showed <700 MS/MS similarity score. Instead of a stand-alone tool, CFM-ID 4.0 might be useful to boost candidate structures in the greater context of identification workflows.
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Affiliation(s)
- Parker Ladd Bremer
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Arpana Vaniya
- West Coast Metabolomics Center for Compound Identification, UC Davis Genome Center, University of California Davis, Davis, California 95616, United States
| | - Tobias Kind
- West Coast Metabolomics Center for Compound Identification, UC Davis Genome Center, University of California Davis, Davis, California 95616, United States
| | - Shunyang Wang
- Department of Chemistry, University of California Davis, Davis, California 95616, United States
| | - Oliver Fiehn
- West Coast Metabolomics Center for Compound Identification, UC Davis Genome Center, University of California Davis, Davis, California 95616, United States
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21
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King E, Overstreet R, Nguyen J, Ciesielski D. Augmentation of MS/MS Libraries with Spectral Interpolation for Improved Identification. J Chem Inf Model 2022; 62:3724-3733. [PMID: 35905451 PMCID: PMC9400100 DOI: 10.1021/acs.jcim.2c00620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Tandem mass spectrometry (MS/MS) is a primary tool for
the identification
of small molecules and metabolites where resultant spectra are most
commonly identified by matching them with spectra in MS/MS reference
libraries. The high degree of variability in MS/MS spectrum acquisition
techniques and parameters creates a significant challenge for building
standardized reference libraries. Here we present a method to improve
the usefulness of existing MS/MS libraries by augmenting available
experimental spectra data sets with statistically interpolated spectra
at unreported collision energies. We find that highly accurate spectral
approximations can be interpolated from as few as three experimental
spectra and that the interpolated spectra will be consistent with
true spectra gathered from the same instrument as the experimental
spectra. Supplementing existing spectral databases with interpolated
spectra yields consistent improvements to identification accuracy
on a range of instruments and precursor types. Applying this method
yields significant improvements (∼10% more spectra correctly
identified) on large data sets (2000–10 000 spectra),
indicating this is a quick yet adept tool for improving spectral matching
in situations where available reference libraries are not yet sufficient.
We also find improvements of matching spectra across instrument types
(between an Agilent Q-TOF and an Orbitrap Elite), at high collision
energies (50–90 eV), and with smaller data sets available through
MassBank.
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Affiliation(s)
- Ethan King
- Computing and Analytics Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Richard Overstreet
- Signature Science and Technology Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Julia Nguyen
- Computing and Analytics Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Danielle Ciesielski
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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22
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Schnegotzki R, Koopman J, Grimme S, Süssmuth RD. Quantum Chemistry-based Molecular Dynamics Simulations as a Tool for the Assignment of ESI-MS/MS Spectra of Drug Molecules. Chemistry 2022; 28:e202200318. [PMID: 35235707 PMCID: PMC9325386 DOI: 10.1002/chem.202200318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Indexed: 11/08/2022]
Abstract
In organic mass spectrometry, fragment ions provide important information on the analyte as a central part of its structure elucidation. With increasing molecular size and possible protonation sites, the potential energy surface (PES) of the analyte can become very complex, which results in a large number of possible fragmentation patterns. Quantum chemical (QC) calculations can help here, enabling the fast calculation of the PES and thus enhancing the mass spectrometry-based structure elucidation processes. In this work, the previously unknown fragmentation pathways of the two drug molecules Nateglinide (45 atoms) and Zopiclone (51 atoms) were investigated using a combination of generic formalisms and calculations conducted with the Quantum Chemical Mass Spectrometry (QCxMS) program. The computations of the de novo fragment spectra were conducted with the semi-empirical GFNn-xTB (n=1, 2) methods and compared against Orbitrap measured electrospray ionization (ESI) spectra in positive ion mode. It was found that the unbiased QC calculations are particularly suitable to predict non-evident fragment ion structures, sometimes contrasting the accepted generic formulation of fragment ion structures from electron migration rules, where the "true" ion fragment structures are approximated. For the first time, all fragment and intermediate structures of these large-sized molecules could be elucidated completely and routinely using this merger of methods, finding new undocumented mechanisms, that are not considered in common rules published so far. Given the importance of ESI for medicinal chemistry, pharmacokinetics, and metabolomics, this approach can significantly enhance the mass spectrometry-based structure elucidation processes and contribute to the understanding of previously unknown fragmentation pathways.
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Affiliation(s)
- Romina Schnegotzki
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, 10623, Berlin, Germany
| | - Jeroen Koopman
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115, Bonn, Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115, Bonn, Germany
| | - Roderich D Süssmuth
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 124, 10623, Berlin, Germany
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23
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Kostyukevich Y, Sosnin S, Osipenko S, Kovaleva O, Rumiantseva L, Kireev A, Zherebker A, Fedorov M, Nikolaev EN. PyFragMS-A Web Tool for the Investigation of the Collision-Induced Fragmentation Pathways. ACS OMEGA 2022; 7:9710-9719. [PMID: 35350354 PMCID: PMC8945079 DOI: 10.1021/acsomega.1c07272] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 02/28/2022] [Indexed: 05/13/2023]
Abstract
Dissociation induced by the accumulation of internal energy via collisions of ions with neutral molecules is one of the most important fragmentation techniques in mass spectrometry (MS), and the identification of small singly charged molecules is based mainly on the consideration of the fragmentation spectrum. Many research studies have been dedicated to the creation of databases of experimentally measured tandem mass spectrometry (MS/MS) spectra (such as MzCloud, Metlin, etc.) and developing software for predicting MS/MS fragments in silico from the molecular structure (such as MetFrag, CFM-ID, CSI:FingerID, etc.). However, the fragmentation mechanisms and pathways are still not fully understood. One of the limiting obstacles is that protomers (positive ions protonated at different sites) produce different fragmentation spectra, and these spectra overlap in the case of the presence of different protomers. Here, we are proposing to use a combination of two powerful approaches: computing fragmentation trees that carry information of all consecutive fragmentations and consideration of the MS/MS data of isotopically labeled compounds. We have created PyFragMS-a web tool consisting of a database of annotated MS/MS spectra of isotopically labeled molecules (after H/D and/or 16O/18O exchange) and a collection of instruments for computing fragmentation trees for an arbitrary molecule. Using PyFragMS, we investigated how the site of protonation influences the fragmentation pathway for small molecules. Also, PyFragMS offers capabilities for performing database search when MS/MS data of the isotopically labeled compounds are taken into account.
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24
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Evaluating the Accuracy of the QCEIMS Approach for Computational Prediction of Electron Ionization Mass Spectra of Purines and Pyrimidines. Metabolites 2022; 12:metabo12010068. [PMID: 35050190 PMCID: PMC8779335 DOI: 10.3390/metabo12010068] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 01/08/2022] [Accepted: 01/09/2022] [Indexed: 12/04/2022] Open
Abstract
Mass spectrometry is the most commonly used method for compound annotation in metabolomics. However, most mass spectra in untargeted assays cannot be annotated with specific compound structures because reference mass spectral libraries are far smaller than the complement of known molecules. Theoretically predicted mass spectra might be used as a substitute for experimental spectra especially for compounds that are not commercially available. For example, the Quantum Chemistry Electron Ionization Mass Spectra (QCEIMS) method can predict 70 eV electron ionization mass spectra from any given input molecular structure. In this work, we investigated the accuracy of QCEIMS predictions of electron ionization (EI) mass spectra for 80 purine and pyrimidine derivatives in comparison to experimental data in the NIST 17 database. Similarity scores between every pair of predicted and experimental spectra revealed that 45% of the compounds were found as the correct top hit when QCEIMS predicted spectra were matched against the NIST17 library of >267,000 EI spectra, and 74% of the compounds were found within the top 10 hits. We then investigated the impact of matching, missing, and additional fragment ions in predicted EI mass spectra versus ion abundances in MS similarity scores. We further include detailed studies of fragmentation pathways such as retro Diels–Alder reactions to predict neutral losses of (iso)cyanic acid, hydrogen cyanide, or cyanamide in the mass spectra of purines and pyrimidines. We describe how trends in prediction accuracy correlate with the chemistry of the input compounds to better understand how mechanisms of QCEIMS predictions could be improved in future developments. We conclude that QCEIMS is useful for generating large-scale predicted mass spectral libraries for identification of compounds that are absent from experimental libraries and that are not commercially available.
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25
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Ketkaew R, Creazzo F, Luber S. Closer Look at Inverse Electron Demand Diels–Alder and Nucleophilic Addition Reactions on s-Tetrazines Using Enhanced Sampling Methods. Top Catal 2021; 65:1-17. [PMID: 35153451 PMCID: PMC8816378 DOI: 10.1007/s11244-021-01516-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/25/2021] [Indexed: 12/30/2022]
Abstract
Inverse electron demand [4+2] Diels–Alder (iEDDA) reactions as well as unprecedented nucleophilic (azaphilic) additions of R-substituted silyl-enol ethers (where R is Phenyl, Methyl, and Hydrogen) to 1,2,4,5-tetrazine (s-tetrazine) catalyzed by \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {BF}_{3}$$\end{document}BF3 have recently been discovered (Simon et al. in Org Lett 23(7):2426–2430, 2021), where static calculations were employed for calculation of activation energies. In order to have a more realistic dynamic description of these reactions in explicit solution at ambient conditions, in this work we use a semiempirical tight-binding method combined with enhanced sampling techniques to calculate free energy surfaces (FESs) of the iEDDA and azaphilic addition reactions. Relevant products of not only s-tetrazine but also its derivatives such as \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {BF}_{3}$$\end{document}BF3-mediated s-tetrazine adducts are investigated. We reconstruct the FESs of the iEDDA and azaphilic addition reactions using metadynamics and blue moon ensemble, and compare the ability of different collective variables (CVs) including bond distances, Social PeRmutation INvarianT (SPRINT) coordinates, and path-CV to describe the reaction pathway. We find that when a bulky Phenyl is used as a substituent at the dienophile the azaphilic addition is preferred over the iEDDA reaction. In addition, we also investigate the effect of \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {BF}_{3}$$\end{document}BF3 in the diene and steric hindrance in the dienophile on the competition between the iEDDA and azaphilic addition reactions, providing chemical insight for reaction design.
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Affiliation(s)
- Rangsiman Ketkaew
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Fabrizio Creazzo
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Sandra Luber
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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26
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Chernicharo FCS, Modesto-Costa L, Borges I. Simulation of the electron ionization mass spectra of the Novichok nerve agent. JOURNAL OF MASS SPECTROMETRY : JMS 2021; 56:e4779. [PMID: 34407561 DOI: 10.1002/jms.4779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 07/19/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
Novichok is one of the most feared and controversial nerve agents, which existence was confirmed only after the Salisbury attack in 2018. A new attack on August 2020, in Russia, was confirmed. After the 2018 attack, the agent was included in the list of the most dangerous chemicals of the Chemical Weapons Convention (CWC). However, information related to its electron ionization mass spectrometry (EI/MS), essential for unambiguous identification, is scarce. Therefore, investigations about Novichok EI/MS are urgent. In this work, we employed Born-Oppenheimer molecular dynamics through the Quantum Chemistry Electron Ionization Mass Spectrometry (QCEIMS) method to simulate and rationalize the EI/MS spectra and fragmentation pathways of 32 Novichok molecules recently incorporated into the CWC. The comparison of additional simulations with the measured EI spectrum of another Novichok analog is very favorable. A general scheme of the fragmentation pathways derived from simulation results was presented. The present results will be useful for elucidation and prediction of the EI spectra and fragmentation pathways of the dangerous Novichok nerve agent.
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Affiliation(s)
| | - Lucas Modesto-Costa
- Departamento de Química, Instituto Militar de Engenharia, Rio de Janeiro, RJ, Brazil
| | - Itamar Borges
- Departamento de Química, Instituto Militar de Engenharia, Rio de Janeiro, RJ, Brazil
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27
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Zubatyuk R, Smith JS, Nebgen BT, Tretiak S, Isayev O. Teaching a neural network to attach and detach electrons from molecules. Nat Commun 2021; 12:4870. [PMID: 34381051 PMCID: PMC8357920 DOI: 10.1038/s41467-021-24904-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 07/01/2021] [Indexed: 02/07/2023] Open
Abstract
Interatomic potentials derived with Machine Learning algorithms such as Deep-Neural Networks (DNNs), achieve the accuracy of high-fidelity quantum mechanical (QM) methods in areas traditionally dominated by empirical force fields and allow performing massive simulations. Most DNN potentials were parametrized for neutral molecules or closed-shell ions due to architectural limitations. In this work, we propose an improved machine learning framework for simulating open-shell anions and cations. We introduce the AIMNet-NSE (Neural Spin Equilibration) architecture, which can predict molecular energies for an arbitrary combination of molecular charge and spin multiplicity with errors of about 2-3 kcal/mol and spin-charges with error errors ~0.01e for small and medium-sized organic molecules, compared to the reference QM simulations. The AIMNet-NSE model allows to fully bypass QM calculations and derive the ionization potential, electron affinity, and conceptual Density Functional Theory quantities like electronegativity, hardness, and condensed Fukui functions. We show that these descriptors, along with learned atomic representations, could be used to model chemical reactivity through an example of regioselectivity in electrophilic aromatic substitution reactions.
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Affiliation(s)
- Roman Zubatyuk
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Justin S Smith
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Benjamin T Nebgen
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Sergei Tretiak
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM, USA
- Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM, USA
| | - Olexandr Isayev
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA, USA.
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28
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Koopman J, Grimme S. From QCEIMS to QCxMS: A Tool to Routinely Calculate CID Mass Spectra Using Molecular Dynamics. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1735-1751. [PMID: 34080847 DOI: 10.1021/jasms.1c00098] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Mass spectrometry (MS) is a powerful tool in chemical research and substance identification. For the computational modeling of electron ionization MS, we have developed the quantum-chemical electron ionization mass spectra (QCEIMS) program. Here, we present an extension of QCEIMS to calculate collision-induced dissociation (CID) spectra. The more general applicability is accounted for by the new name QCxMS, where "x" refers to EI or CID. To this end, fragmentation and rearrangement reactions are computed "on-the-fly" in Born-Oppenheimer molecular dynamics (MD) simulations with the semiempirical GFN2-xTB Hamiltonian, which provides an efficient quantum mechanical description of all elements up to Z = 86 (Rn). Through the explicit modeling of multicollision processes between precursor ions and neutral gas atoms as well as temperature-induced decomposition reactions, QCxMS provides detailed insight into the collision kinetics and fragmentation pathways. In combination with the CREST program to determine the preferential protonation sites, QCxMS becomes the first standalone MD-based program that can predict mass spectra based solely on molecular structures as input. We demonstrate this for six organic molecules with masses ranging from 159 to 296 Da, for which QCxMS yields CID spectra in reasonable agreement with experiments.
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Affiliation(s)
- Jeroen Koopman
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
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29
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Schreckenbach SA, Anderson JSM, Koopman J, Grimme S, Simpson MJ, Jobst KJ. Predicting the Mass Spectra of Environmental Pollutants Using Computational Chemistry: A Case Study and Critical Evaluation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:1508-1518. [PMID: 33982573 DOI: 10.1021/jasms.1c00078] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Organic pollutants can be identified by comparing their electron ionization (EI) mass spectra with those in libraries or obtained from authentic standards. Nevertheless, libraries are incomplete; standards may be unavailable or too costly, or their synthesis may be too time-consuming. This study evaluates the performance of quantum chemical electron ionization mass spectrometry (QCEIMS) vis-à-vis competitive fragmentation modeling (CFM) for suspect screening and unknown identification. EI mass spectra of 35 compounds, including halogenated organics, organophosphorus flame retardants (OPFRs), and disinfection byproducts were computed. Computational results were compared with EI mass spectra compiled in the NIST Library as well as collision-induced dissociation (CID) mass spectra obtained from radical cations M•+ generated by charge-exchange atmospheric pressure chemical ionization (APCI). The results indicate that QCEIMS performs equivalently or better than CFM. Average match factors between computed and experimental (NIST) EI mass spectra were 656 vs 503 for the halogenated organics, and on average, QCEIMS predicted 55% of the products generated by CID vs 17% predicted by CFM. QCEIMS predicted 37% of the OPFR CID products whereas CFM predicted 29%. QCEIMS performed comparably to a commercial combinatorial fragmentation method for suspect screening of a dust sample, identifying 19/20 targets. Examples of unknown pollutants, whose reference spectra were unavailable at the time of discovery, are also presented. The computational results suggest that QCEIMS can help guide the analyst in obtaining authentic standards and raise the possibility that, with advances in computing, an unknown may eventually be confirmed in hours as opposed to the days or months required to obtain authentic standards.
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Affiliation(s)
- Sophia A Schreckenbach
- Departments of Chemistry and Physical and Environmental Sciences, University of Toronto, Toronto, Ontario M1C 1A4, Canada
| | - James S M Anderson
- Institute of Chemistry, Universidad Nacional Autónoma de México, Mexico City 04510, Mexico
| | - Jeroen Koopman
- Mulliken Center for Theoretical Chemistry, University of Bonn, 53115 Bonn, Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, University of Bonn, 53115 Bonn, Germany
| | - Myrna J Simpson
- Departments of Chemistry and Physical and Environmental Sciences, University of Toronto, Toronto, Ontario M1C 1A4, Canada
| | - Karl J Jobst
- Department of Chemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador A1B 3X7, Canada
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30
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Misra BB. Advances in high resolution GC-MS technology: a focus on the application of GC-Orbitrap-MS in metabolomics and exposomics for FAIR practices. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2021; 13:2265-2282. [PMID: 33987631 DOI: 10.1039/d1ay00173f] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Gas chromatography-mass spectrometry (GC-MS) provides a complementary analytical platform for capturing volatiles, non-polar and (derivatized) polar metabolites and exposures from a diverse array of matrixes. High resolution (HR) GC-MS as a data generation platform can capture data on analytes that are usually not detectable/quantifiable in liquid chromatography mass-spectrometry-based solutions. With the rise of high-resolution accurate mass (HRAM) GC-MS systems such as GC-Orbitrap-MS in the last decade after the time-of-flight (ToF) renaissance, numerous applications have been found in the fields of metabolomics and exposomics. In a short span of time, a multitude of studies have used GC-Orbitrap-MS to generate exciting new high throughput data spanning from diverse basic to applied research areas. The GC-Orbitrap-MS has found application in both targeted and untargeted efforts for capturing metabolomes and exposomes across diverse studies. In this review, I capture and summarize all the reported studies to date, and provide a snapshot of the milieu of commercial and open-source software solutions, spectral libraries, and informatics solutions available to a GC-Orbitrap-MS system instrument user or a data analyst dealing with these datasets. Lastly, but importantly, I provide an account on data sharing and meta-data capturing solutions that are available to make HRAM GC-MS based metabolomics and exposomics studies findable, accessible, interoperable, and reproducible (FAIR). These FAIR practices would allow data generators and users of GC-HRMS instruments to help the community of GC-MS researchers to collaborate and co-develop exciting tools and algorithms in the future.
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Affiliation(s)
- Biswapriya B Misra
- Independent Researcher, Pine-211, Raintree Park Dwaraka Krishna, Namburu, AP-522508, India.
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31
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Borges R, Colby SM, Das S, Edison AS, Fiehn O, Kind T, Lee J, Merrill AT, Merz KM, Metz TO, Nunez JR, Tantillo DJ, Wang LP, Wang S, Renslow RS. Quantum Chemistry Calculations for Metabolomics. Chem Rev 2021; 121:5633-5670. [PMID: 33979149 PMCID: PMC8161423 DOI: 10.1021/acs.chemrev.0c00901] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Indexed: 02/07/2023]
Abstract
A primary goal of metabolomics studies is to fully characterize the small-molecule composition of complex biological and environmental samples. However, despite advances in analytical technologies over the past two decades, the majority of small molecules in complex samples are not readily identifiable due to the immense structural and chemical diversity present within the metabolome. Current gold-standard identification methods rely on reference libraries built using authentic chemical materials ("standards"), which are not available for most molecules. Computational quantum chemistry methods, which can be used to calculate chemical properties that are then measured by analytical platforms, offer an alternative route for building reference libraries, i.e., in silico libraries for "standards-free" identification. In this review, we cover the major roadblocks currently facing metabolomics and discuss applications where quantum chemistry calculations offer a solution. Several successful examples for nuclear magnetic resonance spectroscopy, ion mobility spectrometry, infrared spectroscopy, and mass spectrometry methods are reviewed. Finally, we consider current best practices, sources of error, and provide an outlook for quantum chemistry calculations in metabolomics studies. We expect this review will inspire researchers in the field of small-molecule identification to accelerate adoption of in silico methods for generation of reference libraries and to add quantum chemistry calculations as another tool at their disposal to characterize complex samples.
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Affiliation(s)
- Ricardo
M. Borges
- Walter
Mors Institute of Research on Natural Products, Federal University of Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Sean M. Colby
- Biological
Science Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
| | - Susanta Das
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Arthur S. Edison
- Departments
of Genetics and Biochemistry and Molecular Biology, Complex Carbohydrate
Research Center and Institute of Bioinformatics, University of Georgia, Athens, Georgia 30602, United States
| | - Oliver Fiehn
- West
Coast Metabolomics Center for Compound Identification, UC Davis Genome
Center, University of California, Davis, California 95616, United States
| | - Tobias Kind
- West
Coast Metabolomics Center for Compound Identification, UC Davis Genome
Center, University of California, Davis, California 95616, United States
| | - Jesi Lee
- West
Coast Metabolomics Center for Compound Identification, UC Davis Genome
Center, University of California, Davis, California 95616, United States
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Amy T. Merrill
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Kenneth M. Merz
- Department
of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Thomas O. Metz
- Biological
Science Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
| | - Jamie R. Nunez
- Biological
Science Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
| | - Dean J. Tantillo
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Lee-Ping Wang
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Shunyang Wang
- West
Coast Metabolomics Center for Compound Identification, UC Davis Genome
Center, University of California, Davis, California 95616, United States
- Department
of Chemistry, University of California, Davis, California 95616, United States
| | - Ryan S. Renslow
- Biological
Science Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
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32
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Krettler CA, Thallinger GG. A map of mass spectrometry-based in silico fragmentation prediction and compound identification in metabolomics. Brief Bioinform 2021; 22:6184408. [PMID: 33758925 DOI: 10.1093/bib/bbab073] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Revised: 01/29/2021] [Accepted: 02/12/2021] [Indexed: 12/27/2022] Open
Abstract
Metabolomics, the comprehensive study of the metabolome, and lipidomics-the large-scale study of pathways and networks of cellular lipids-are major driving forces in enabling personalized medicine. Complicated and error-prone data analysis still remains a bottleneck, however, especially for identifying novel metabolites. Comparing experimental mass spectra to curated databases containing reference spectra has been the gold standard for identification of compounds, but constructing such databases is a costly and time-demanding task. Many software applications try to circumvent this process by utilizing cutting-edge advances in computational methods-including quantum chemistry and machine learning-and simulate mass spectra by performing theoretical, so called in silico fragmentations of compounds. Other solutions concentrate directly on experimental spectra and try to identify structural properties by investigating reoccurring patterns and the relationships between them. The considerable progress made in the field allows recent approaches to provide valuable clues to expedite annotation of experimental mass spectra. This review sheds light on individual strengths and weaknesses of these tools, and attempts to evaluate them-especially in view of lipidomics, when considering complex mixtures found in biological samples as well as mass spectrometer inter-instrument variability.
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Affiliation(s)
- Christoph A Krettler
- Institute of Biomedical Informatics, Graz University of Technology, Stremayrgasse 16/I, 8010, Graz, Austria.,Omics Center Graz, BioTechMed-Graz, Stiftingtalstrasse 24, 8010, Graz, Austria
| | - Gerhard G Thallinger
- Institute of Biomedical Informatics, Graz University of Technology, Stremayrgasse 16/I, 8010, Graz, Austria.,Omics Center Graz, BioTechMed-Graz, Stiftingtalstrasse 24, 8010, Graz, Austria
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33
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Aguirre NF, Díaz-Tendero S, Hervieux PA, Alcamí M, Chabot M, Béroff K, Martín F. Charge and energy sharing in the fragmentation of astrophysically relevant carbon clusters. Theor Chem Acc 2021. [DOI: 10.1007/s00214-020-02702-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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34
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Carrà A, Spezia R. In Silico
Tandem Mass Spectrometer: an Analytical and Fundamental Tool. ACTA ACUST UNITED AC 2021. [DOI: 10.1002/cmtd.202000071] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Andrea Carrà
- Agilent Technologies Italia Via Piero Gobetti 2/C 20063 Cernusco SN, Milano Italy
| | - Riccardo Spezia
- Laboratoire de Chimie Théorique Sorbonne Université, UMR 7616 CNRS 4, Place Jussieu 75005 Paris France
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35
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Synthesis, crystal structure, anti-cancer, anti-inflammatory anti-oxidant and quantum chemical studies of 4-(pyrrolidine-2,5‑dione‑1-yl)phenol. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2020.129267] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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36
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Wang S, Kind T, Tantillo DJ, Fiehn O. Predicting in silico electron ionization mass spectra using quantum chemistry. J Cheminform 2020; 12:63. [PMID: 33372633 PMCID: PMC7576811 DOI: 10.1186/s13321-020-00470-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 10/13/2020] [Indexed: 12/20/2022] Open
Abstract
Compound identification by mass spectrometry needs reference mass spectra. While there are over 102 million compounds in PubChem, less than 300,000 curated electron ionization (EI) mass spectra are available from NIST or MoNA mass spectral databases. Here, we test quantum chemistry methods (QCEIMS) to generate in silico EI mass spectra (MS) by combining molecular dynamics (MD) with statistical methods. To test the accuracy of predictions, in silico mass spectra of 451 small molecules were generated and compared to experimental spectra from the NIST 17 mass spectral library. The compounds covered 43 chemical classes, ranging up to 358 Da. Organic oxygen compounds had a lower matching accuracy, while computation time exponentially increased with molecular size. The parameter space was probed to increase prediction accuracy including initial temperatures, the number of MD trajectories and impact excess energy (IEE). Conformational flexibility was not correlated to the accuracy of predictions. Overall, QCEIMS can predict 70 eV electron ionization spectra of chemicals from first principles. Improved methods to calculate potential energy surfaces (PES) are still needed before QCEIMS mass spectra of novel molecules can be generated at large scale.
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Affiliation(s)
- Shunyang Wang
- West Coast Metabolomics Center, UC Davis Genome Center, University of California, 451 Health Sciences Drive, Davis, CA, 95616, USA.,Department of Chemistry, University of California, 1 Shields Ave, Davis, CA, 95616, USA
| | - Tobias Kind
- West Coast Metabolomics Center, UC Davis Genome Center, University of California, 451 Health Sciences Drive, Davis, CA, 95616, USA
| | - Dean J Tantillo
- Department of Chemistry, University of California, 1 Shields Ave, Davis, CA, 95616, USA
| | - Oliver Fiehn
- West Coast Metabolomics Center, UC Davis Genome Center, University of California, 451 Health Sciences Drive, Davis, CA, 95616, USA.
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37
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Dietrich CA, Schuldt R, Born D, Solodenko H, Schmitz G, Kästner J. Evaporation and Fragmentation of Organic Molecules in Strong Electric Fields Simulated with DFT. J Phys Chem A 2020; 124:8633-8642. [PMID: 32946231 DOI: 10.1021/acs.jpca.0c06887] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Atom probe tomography allows us to measure the three-dimensional composition of materials with up to atomic resolution by evaporating the material using high electric fields. Initially developed for metals, it is increasingly used for covalently bound structures. To aid the interpretation of the obtained fragmentation pattern, we modeled the fragmentation and desorption of self-assembled monolayers of thiolate molecules on a gold surface in strong electrostatic fields using density functional theory. We used a cluster model and a periodic model of amino-undecanethiolate, NH2(CH2)11S, and fluoro-decanethiolate, CF3(CF2)7(CH2)2S. In the former molecule, the fragment CH2NH2+ was found to evaporate at fields of 5.4-7.7 V/nm. It was followed by different hydrocarbon fragments. Fluoro-decanethiolate evaporates CF3+ at fields of 5.7-6.7 V/nm in the cluster model and at 15.4-23.1 V/nm in the periodic model, followed by CF2+ and C2F42+. Detailed analysis of the electronic structure during the evaporation process revealed a stepwise accumulation of the charge in the head groups exposed to the strongest fields, followed by dissociation of covalent bonds. These observations will facilitate the analysis of atom probe experiments of covalently bound structures.
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Affiliation(s)
- Carolin A Dietrich
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Robin Schuldt
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Daniel Born
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Helena Solodenko
- Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Guido Schmitz
- Institute for Materials Science, University of Stuttgart, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Johannes Kästner
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
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38
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Weidner P, Voronova K, Bodi A, Sztáray B. Dissociative photoionization of 1,3-dioxolane: We need six channels to fit the elephant. JOURNAL OF MASS SPECTROMETRY : JMS 2020; 55:e4522. [PMID: 32510769 DOI: 10.1002/jms.4522] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 03/29/2020] [Accepted: 04/01/2020] [Indexed: 06/11/2023]
Abstract
The dissociative photoionization of 1,3-dioxolane was studied by photoelectron photoion coincidence (PEPICO) spectroscopy in the photon energy range of 9.5-13.5 eV. Our statistical thermodynamics model shows that a total of six dissociation channels are involved in the formation of three fragment ions, namely, C3 H5 O2 + (m/z 73), C2 H5 O+ (m/z 45), and C2 H4 O+ (m/z 44), with two channels contributing to the formation of each. By comparing the results of ab initio quantum chemical calculations to the experimentally derived appearance energies of the fragment ions, the most likely mechanisms for these unimolecular dissociation reactions are proposed, including a description of the relevant parts of the potential energy surface.
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Affiliation(s)
- Peter Weidner
- Department of Chemistry, University of the Pacific, Stockton, California, 95211, USA
| | - Krisztina Voronova
- Department of Chemistry, University of Nevada, Reno, Reno, Nevada, 89557, USA
| | - Andras Bodi
- Laboratory for Synchrotron Radiation and Femtochemistry, Paul Scherrer Institute, 5232, Villigen, Switzerland
| | - Bálint Sztáray
- Department of Chemistry, University of the Pacific, Stockton, California, 95211, USA
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39
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Tikhonov DS, Datta A, Chopra P, Steber AL, Manschwetus B, Schnell M. Approaching black-box calculations of pump-probe fragmentation dynamics of polyatomic molecules. Z PHYS CHEM 2020. [DOI: 10.1515/zpch-2020-0009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Abstract
A general framework for the simulation of ultrafast pump-probe time resolved experiments based on Born-Oppenheimer molecular dynamics (BOMD) is presented. Interaction of the molecular species with a laser is treated by a simple maximum entropy distribution of the excited state occupancies. The latter decay of the electronic excitation into the vibrations is based on an on-the-fly estimation of the rate of the internal conversion, while the energy is distributed in a thermostat-like fashion. The approach was tested by reproducing the results of previous femtosecond studies on ethylene, naphthalene and new results for phenanthrene.
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Affiliation(s)
- Denis S. Tikhonov
- Deutsches Elektronen-Synchrotron (DESY) , Notkestr. 85 , D-22607 Hamburg , Germany
- Institute of Physical Chemistry , Christian-Albrechts-Universität zu Kiel , Max-Eyth-Str. 1 , D-24118 Kiel , Germany
| | - Amlan Datta
- Department of Physical Sciences , Indian Institute of Science Education and Research Kolkata , Mohanpur , Nadia , West Bengal 741246 , India
| | - Pragya Chopra
- Deutsches Elektronen-Synchrotron (DESY) , Notkestr. 85 , D-22607 Hamburg , Germany
- Institute of Physical Chemistry , Christian-Albrechts-Universität zu Kiel , Max-Eyth-Str. 1 , D-24118 Kiel , Germany
| | - Amanda L. Steber
- Deutsches Elektronen-Synchrotron (DESY) , Notkestr. 85 , D-22607 Hamburg , Germany
- Institute of Physical Chemistry , Christian-Albrechts-Universität zu Kiel , Max-Eyth-Str. 1 , D-24118 Kiel , Germany
| | - Bastian Manschwetus
- Deutsches Elektronen-Synchrotron (DESY) , Notkestr. 85 , D-22607 Hamburg , Germany
| | - Melanie Schnell
- Deutsches Elektronen-Synchrotron (DESY) , Notkestr. 85 , D-22607 Hamburg , Germany
- Institute of Physical Chemistry , Christian-Albrechts-Universität zu Kiel , Max-Eyth-Str. 1 , D-24118 Kiel , Germany
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40
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Bannwarth C, Caldeweyher E, Ehlert S, Hansen A, Pracht P, Seibert J, Spicher S, Grimme S. Extended
tight‐binding
quantum chemistry methods. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2020. [DOI: 10.1002/wcms.1493] [Citation(s) in RCA: 218] [Impact Index Per Article: 54.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Christoph Bannwarth
- Department of Chemistry and The PULSE Institute Stanford University Stanford California USA
| | - Eike Caldeweyher
- Mulliken Center for Theoretical Chemistry Rheinische Friedrich‐Wilhelms‐Universität Bonn Bonn Germany
| | - Sebastian Ehlert
- Mulliken Center for Theoretical Chemistry Rheinische Friedrich‐Wilhelms‐Universität Bonn Bonn Germany
| | - Andreas Hansen
- Mulliken Center for Theoretical Chemistry Rheinische Friedrich‐Wilhelms‐Universität Bonn Bonn Germany
| | - Philipp Pracht
- Mulliken Center for Theoretical Chemistry Rheinische Friedrich‐Wilhelms‐Universität Bonn Bonn Germany
| | - Jakob Seibert
- Mulliken Center for Theoretical Chemistry Rheinische Friedrich‐Wilhelms‐Universität Bonn Bonn Germany
| | - Sebastian Spicher
- Mulliken Center for Theoretical Chemistry Rheinische Friedrich‐Wilhelms‐Universität Bonn Bonn Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry Rheinische Friedrich‐Wilhelms‐Universität Bonn Bonn Germany
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41
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Neugebauer H, Bohle F, Bursch M, Hansen A, Grimme S. Benchmark Study of Electrochemical Redox Potentials Calculated with Semiempirical and DFT Methods. J Phys Chem A 2020; 124:7166-7176. [DOI: 10.1021/acs.jpca.0c05052] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Hagen Neugebauer
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
| | - Fabian Bohle
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
| | - Markus Bursch
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
| | - Andreas Hansen
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
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42
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Ji H, Deng H, Lu H, Zhang Z. Predicting a Molecular Fingerprint from an Electron Ionization Mass Spectrum with Deep Neural Networks. Anal Chem 2020; 92:8649-8653. [DOI: 10.1021/acs.analchem.0c01450] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Hongchao Ji
- College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, PR China
| | - Hanzi Deng
- College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, PR China
| | - Hongmei Lu
- College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, PR China
| | - Zhimin Zhang
- College of Chemistry and Chemical Engineering, Central South University, Changsha, Hunan 410083, PR China
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43
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Chernicharo FCS, Modesto-Costa L, Borges I. Molecular dynamics simulation of the electron ionization mass spectrum of tabun. JOURNAL OF MASS SPECTROMETRY : JMS 2020; 55:e4513. [PMID: 32212286 DOI: 10.1002/jms.4513] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 03/05/2020] [Accepted: 03/11/2020] [Indexed: 06/10/2023]
Abstract
Tabun (ethyl N,N-dimethylphosphoramidocyanidate), or GA, is a chemical warfare nerve agent produced during the World War II. The synthesis of its analogs is rather simple; thus, it is a significant threat. Furthermore, experiments with tabun and other nerve agents are greatly limited by the involved life risks and the severe restrictions imposed by the Chemical Weapons Convention. For these reasons, accurate theoretical assignment of fragmentation pathways can be especially important. In this work, we employ the Quantum Chemistry Electron Ionization Mass Spectra method, which combines molecular dynamics, quantum chemistry methods, and stochastic approaches, to accurately investigate the electron ionization/mass spectrometry (EI/MS) fragmentation spectrum and pathways of the tabun molecule. We found that different rearrangement reactions occur including a McLafferty involving the nitrile group. An essential and characteristic pathway for identification of tabun and analogs, a two-step fragmentation producing the m/z 70 ion, was confirmed. The present results will be also useful to predict EI/MS spectrum and fragmentation pathways of other members of the tabun family, namely, the O-alkyl/cycloalkyl N,N-dialkyl (methyl, ethyl, isopropyl, or propyl) phosphoramidocyanidates.
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Affiliation(s)
- Francisco C S Chernicharo
- Department of Chemistry, Military Institute of Engineering, Praça Gen Tiburcio, 80, Rio de Janeiro, RJ, Brazil
| | - Lucas Modesto-Costa
- Department of Chemistry, Military Institute of Engineering, Praça Gen Tiburcio, 80, Rio de Janeiro, RJ, Brazil
| | - Itamar Borges
- Department of Chemistry, Military Institute of Engineering, Praça Gen Tiburcio, 80, Rio de Janeiro, RJ, Brazil
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44
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Pracht P, Bohle F, Grimme S. Automated exploration of the low-energy chemical space with fast quantum chemical methods. Phys Chem Chem Phys 2020; 22:7169-7192. [PMID: 32073075 DOI: 10.1039/c9cp06869d] [Citation(s) in RCA: 861] [Impact Index Per Article: 215.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We propose and discuss an efficient scheme for the in silico sampling for parts of the molecular chemical space by semiempirical tight-binding methods combined with a meta-dynamics driven search algorithm. The focus of this work is set on the generation of proper thermodynamic ensembles at a quantum chemical level for conformers, but similar procedures for protonation states, tautomerism and non-covalent complex geometries are also discussed. The conformational ensembles consisting of all significantly populated minimum energy structures normally form the basis of further, mostly DFT computational work, such as the calculation of spectra or macroscopic properties. By using basic quantum chemical methods, electronic effects or possible bond breaking/formation are accounted for and a very reasonable initial energetic ranking of the candidate structures is obtained. Due to the huge computational speedup gained by the fast low-cost quantum chemical methods, overall short computation times even for systems with hundreds of atoms (typically drug-sized molecules) are achieved. Furthermore, specialized applications, such as sampling with implicit solvation models or constrained conformational sampling for transition-states, metal-, surface-, or noncovalently bound complexes are discussed, opening many possible applications in modern computational chemistry and drug discovery. The procedures have been implemented in a freely available computer code called CREST, that makes use of the fast and reliable GFNn-xTB methods.
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Affiliation(s)
- Philipp Pracht
- Mulliken Center for Theoretical Chemistry, Universität Bonn, Beringstr. 4, 53115 Bonn, Germany.
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45
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Mapping the optoelectronic property space of small aromatic molecules. Commun Chem 2020; 3:14. [PMID: 36703446 PMCID: PMC9814262 DOI: 10.1038/s42004-020-0256-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 12/19/2019] [Indexed: 01/29/2023] Open
Abstract
Small aromatic molecules and their quinone derivatives find use in organic transistors, solar-cells, thermoelectrics, batteries and photocatalysts. These applications exploit the optoelectronic properties of these molecules and the ease by which such properties can be tuned by the introduction of heteroatoms and/or the addition of functional groups. We perform a high-throughput virtual screening using the xTB family of density functional tight-binding methods to map the optoelectronic property space of ~250,000 molecules. The large volume of data generated allows for a broad understanding of how the presence of heteroatoms and functional groups affect the ionisation potential, electron affinity and optical gap values of these molecular semiconductors, and how the structural features - on their own or in combination with one another - allow access to particular regions of the optoelectronic property space. Finally, we identify the apparent boundaries of the optoelectronic property space for these molecules: regions of property space that appear off limits for any small aromatic molecule.
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46
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Carrà A, Macaluso V, Villalta PW, Spezia R, Balbo S. Fragmentation Spectra Prediction and DNA Adducts Structural Determination. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:2771-2784. [PMID: 31696434 DOI: 10.1007/s13361-019-02348-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 10/04/2019] [Accepted: 10/09/2019] [Indexed: 06/10/2023]
Abstract
In this work, chemical dynamics simulations were optimized and used to predict fragmentation mass spectra for DNA adduct structural determination. O6-methylguanine (O6-Me-G) was used as a simple model adduct to calculate theoretical spectra for comparison with measured high-resolution fragmentation data. An automatic protocol was established to consider the different tautomers accessible at a given energy and obtain final theoretical spectra by insertion of an initial tautomer. In the work reported here, the most stable tautomer was chosen as the initial structure, but in general, any structure could be considered. Allowing for the formation of the various possible tautomers during simulation calculations was found to be important to getting a more complete fragmentation spectrum. The calculated theoretical results reproduce the experimental peaks such that it was possible to determine reaction pathways and product structures. The calculated tautomerization network was crucial to correctly identifying all the observed ion peaks, showing that a mobile proton model holds not only for peptide fragmentation but also for nucleobases. Finally, first principles results were compared to simple machine learning fragmentation models.
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Affiliation(s)
- Andrea Carrà
- Masonic Cancer Center, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA
| | - Veronica Macaluso
- Laboratoire Analyse et Modélisation pour la Biologie et l'Environnement, Université d'Evry, CEA, CNRS, Université Paris Saclay, Bd. F. Mitterrand, 91025, Evry Cedex, France
| | - Peter W Villalta
- Masonic Cancer Center, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA
| | - Riccardo Spezia
- Laboratoire de Chimie Théorique, LCT, CNRS, Sorbonne Université, F. 75005, Paris, France.
| | - Silvia Balbo
- Masonic Cancer Center, University of Minnesota, 2231 6th Street SE, Minneapolis, MN, 55455, USA.
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Majer K, Signorell R, Heringa MF, Goldmann M, Hemberger P, Bodi A. Valence Photoionization of Thymine: Ionization Energies, Vibrational Structure, and Fragmentation Pathways from the Slow to the Ultrafast. Chemistry 2019; 25:14192-14204. [PMID: 31469456 DOI: 10.1002/chem.201903282] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Indexed: 11/06/2022]
Abstract
The photoionization of thymine has been studied by using vacuum ultraviolet radiation and imaging photoelectron photoion coincidence spectroscopy after aerosol flash vaporization and bulk evaporation. The two evaporation techniques have been evaluated by comparison of the photoelectron spectra and breakdown diagrams. The adiabatic ionization energies for the first four electronic states were determined to be 8.922±0.008, 9.851±0.008, 10.30±0.02, and 10.82±0.01 eV. Vibrational features have been assigned for the first three electronic states with the help of Franck-Condon factor calculations based on density functional theory and wave function theory vibrational analysis within the harmonic approximation. The breakdown diagram of thymine, as supported by composite method ab initio calculations, suggests that the main fragment ions are formed in sequential HNCO-, CO-, and H-loss dissociation steps from the thymine parent ion, with the first step corresponding to a retro-Diels-Alder reaction. The dissociation rate constants were extracted from the photoion time-of-flight distributions and used together with the breakdown curves to construct a statistical model to determine 0 K appearance energies of 11.15±0.16 and 11.95±0.09 eV for the m/z 83 and 55 fragment ions, respectively. These results have allowed us to revise previously proposed fragmentation mechanisms and to propose a model for the final, nonstatistical H-loss step in the breakdown diagram, yielding the m/z 54 fragment ion at an appearance energy of 13.24 eV.
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Affiliation(s)
- Katharina Majer
- Paul Scherrer Institute, 5232, Villigen, Switzerland.,Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zürich, 8093, Zürich, Switzerland
| | - Ruth Signorell
- Department of Chemistry and Applied Biosciences, Laboratory of Physical Chemistry, ETH Zürich, 8093, Zürich, Switzerland
| | - Maarten F Heringa
- Paul Scherrer Institute, 5232, Villigen, Switzerland.,Present address: Givaudan Schweiz AG, 8310, Kemptthal, Switzerland
| | - Maximilian Goldmann
- Gymnasium Lerbermatt, 3098, Köniz, Switzerland.,Hochschule Luzern - Technik & Architektur, 6048, Horw, Switzerland
| | | | - Andras Bodi
- Paul Scherrer Institute, 5232, Villigen, Switzerland
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Moumbock AFA, Ntie-Kang F, Akone SH, Li J, Gao M, Telukunta KK, Günther S. An overview of tools, software, and methods for natural product fragment and mass spectral analysis. PHYSICAL SCIENCES REVIEWS 2019. [DOI: 10.1515/psr-2018-0126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Abstract
One major challenge in natural product (NP) discovery is the determination of the chemical structure of unknown metabolites using automated software tools from either GC–mass spectrometry (MS) or liquid chromatography–MS/MS data only. This chapter reviews the existing spectral libraries and predictive computational tools used in MS-based untargeted metabolomics, which is currently a hot topic in NP structure elucidation. We begin by focusing on spectral databases and the general workflow of MS annotation. We then describe software and tools used in MS, particularly those used to predict fragmentation patterns, mass spectral classifiers, and tools for fragmentation trees analysis. We then round up the chapter by looking at more advanced approaches implemented in tools for competitive fragmentation modeling and quantum chemical approaches.
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Koopman J, Grimme S. Calculation of Electron Ionization Mass Spectra with Semiempirical GFNn-xTB Methods. ACS OMEGA 2019; 4:15120-15133. [PMID: 31552357 PMCID: PMC6751715 DOI: 10.1021/acsomega.9b02011] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 08/05/2019] [Indexed: 05/31/2023]
Abstract
In this work, we have tested two different extended tight-binding methods in the framework of the quantum chemistry electron ionization mass spectrometry (QCEIMS) program to calculate electron ionization mass spectra. The QCEIMS approach provides reasonable, first-principles computed spectra, which can be directly compared to experiment. Furthermore, it provides detailed insight into the reaction mechanisms of mass spectrometry experiments. It sheds light upon the complicated fragmentation procedures of bond breakage and structural rearrangements that are difficult to derive otherwise. The required accuracy and computational demands for successful reproduction of a mass spectrum in relation to the underlying quantum chemical method are discussed. To validate the new GFN2-xTB approach, we conduct simulations for 15 organic, transition-metal, and main-group inorganic systems. Major fragmentation patterns are analyzed, and the entire calculated spectra are directly compared to experimental data taken from the literature. We discuss the computational costs and the robustness (outliers) of several calculation protocols presented. Overall, the new, theoretically more sophisticated semiempirical method GFN2-xTB performs well and robustly for a wide range of organic, inorganic, and organometallic systems.
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Affiliation(s)
- Jeroen Koopman
- Mulliken Center for Theoretical
Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
| | - Stefan Grimme
- Mulliken Center for Theoretical
Chemistry, Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
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50
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Przybyłek M, Studziński W, Gackowska A, Gaca J. The use of fast molecular descriptors and artificial neural networks approach in organochlorine compounds electron ionization mass spectra classification. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:28188-28201. [PMID: 31363975 PMCID: PMC6791912 DOI: 10.1007/s11356-019-05968-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2018] [Accepted: 07/12/2019] [Indexed: 06/10/2023]
Abstract
Developing of theoretical tools can be very helpful for supporting new pollutant detection. Nowadays, a combination of mass spectrometry and chromatographic techniques are the most basic environmental monitoring methods. In this paper, two organochlorine compound mass spectra classification systems were proposed. The classification models were developed within the framework of artificial neural networks (ANNs) and fast 1D and 2D molecular descriptor calculations. Based on the intensities of two characteristic MS peaks, namely, [M] and [M-35], two classification criterions were proposed. According to criterion I, class 1 comprises [M] signals with the intensity higher than 800 NIST units, while class 2 consists of signals with the intensity lower or equal than 800. According to criterion II, class 1 consists of [M-35] signals with the intensity higher than 100, while signals with the intensity lower or equal than 100 belong to class 2. As a result of ANNs learning stage, five models for both classification criterions were generated. The external model validation showed that all ANNs are characterized by high predicting power; however, criterion I-based ANNs are much more accurate and therefore are more suitable for analytical purposes. In order to obtain another confirmation, selected ANNs were tested against additional dataset comprising popular sunscreen agents disinfection by-products reported in previous works.
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Affiliation(s)
- Maciej Przybyłek
- Chair and Department of Physical Chemistry, Pharmacy Faculty, Collegium Medicum of Bydgoszcz, Nicolaus Copernicus University in Toruń, Kurpińskiego 5, 85-950, Bydgoszcz, Poland.
| | - Waldemar Studziński
- Faculty of Chemical Technology and Engineering, University of Technology and Life Science, Seminaryjna 3, 85-326, Bydgoszcz, Poland
| | - Alicja Gackowska
- Faculty of Chemical Technology and Engineering, University of Technology and Life Science, Seminaryjna 3, 85-326, Bydgoszcz, Poland
| | - Jerzy Gaca
- Faculty of Chemical Technology and Engineering, University of Technology and Life Science, Seminaryjna 3, 85-326, Bydgoszcz, Poland
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