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Barone V, Fusè M, Lazzari F, Mancini G. Benchmark Structures and Conformational Landscapes of Amino Acids in the Gas Phase: A Joint Venture of Machine Learning, Quantum Chemistry, and Rotational Spectroscopy. J Chem Theory Comput 2023; 19:1243-1260. [PMID: 36731119 PMCID: PMC9979611 DOI: 10.1021/acs.jctc.2c01143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The accurate characterization of prototypical bricks of life can strongly benefit from the integration of high resolution spectroscopy and quantum mechanical computations. We have selected a number of representative amino acids (glycine, alanine, serine, cysteine, threonine, aspartic acid and asparagine) to validate a new computational setup rooted in quantum-chemical computations of increasing accuracy guided by machine learning tools. Together with low-lying energy minima, the barriers ruling their interconversion are evaluated in order to unravel possible fast relaxation paths. Vibrational and thermal effects are also included in order to estimate relative free energies at the temperature of interest in the experiment. The spectroscopic parameters of all the most stable conformers predicted by this computational strategy, which do not have low-energy relaxation paths available, closely match those of the species detected in microwave experiments. Together with their intrinsic interest, these accurate results represent ideal benchmarks for more approximate methods.
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Barone V, Di Grande S, Puzzarini C. Toward Accurate yet Effective Computations of Rotational Spectroscopy Parameters for Biomolecule Building Blocks. MOLECULES (BASEL, SWITZERLAND) 2023; 28:molecules28020913. [PMID: 36677970 PMCID: PMC9863398 DOI: 10.3390/molecules28020913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 01/01/2023] [Accepted: 01/12/2023] [Indexed: 01/19/2023]
Abstract
The interplay of high-resolution rotational spectroscopy and quantum-chemical computations plays an invaluable role in the investigation of biomolecule building blocks in the gas phase. However, quantum-chemical methods suffer from unfavorable scaling with the dimension of the system under consideration. While a complete characterization of flexible systems requires an elaborate multi-step strategy, in this work, we demonstrate that the accuracy obtained by quantum-chemical composite approaches in the prediction of rotational spectroscopy parameters can be approached by a model based on density functional theory. Glycine and serine are employed to demonstrate that, despite its limited cost, such a model is able to predict rotational constants with an accuracy of 0.3% or better, thus paving the way toward the accurate characterization of larger flexible building blocks of biomolecules.
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Barone V. Autobiography of Vincenzo Barone. J Phys Chem A 2022; 126:9143-9146. [DOI: 10.1021/acs.jpca.2c07842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Cicolella A, Romano E, Barone V, De Rosa C, Talarico G. Metallocenes and Beyond for Propene Polymerization: Energy Decomposition of Density Functional Computations Unravels the Different Interplay of Stereoelectronic Effects. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Mendolicchio M, Bloino J, Barone V. Perturb-Then-Diagonalize Vibrational Engine Exploiting Curvilinear Internal Coordinates. J Chem Theory Comput 2022; 18:7603-7619. [PMID: 36322968 DOI: 10.1021/acs.jctc.2c00773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The present paper is devoted to the implementation and validation of a second-order perturbative approach to anharmonic vibrations, followed by variational treatment of strong couplings (GVPT2) based on curvilinear internal coordinates. The main difference with respect to the customary Cartesian-based formulation is that the kinetic energy operator is no longer diagonal, and has to be expanded as well, leading to additional terms which have to be taken into proper account. It is, however, possible to recast all the equations as well-defined generalizations of the corresponding Cartesian-based counterparts, thus achieving a remarkable simplification of the new implementation. Particular attention is paid to the treatment of Fermi resonances with significant number of test cases analyzed fully, validating the new implementation. The results obtained in this work confirm that curvilinear coordinates strongly reduce the strength of inter-mode couplings compared to their Cartesian counterparts. This increases the reliability of low-order perturbative treatments for semi-rigid molecules and paves the way toward the reliable representation of more flexible molecules where small- and large-amplitude motions can be safely decoupled and treated at different levels of theory.
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Teale AM, Helgaker T, Savin A, Adamo C, Aradi B, Arbuznikov AV, Ayers PW, Baerends EJ, Barone V, Calaminici P, Cancès E, Carter EA, Chattaraj PK, Chermette H, Ciofini I, Crawford TD, De Proft F, Dobson JF, Draxl C, Frauenheim T, Fromager E, Fuentealba P, Gagliardi L, Galli G, Gao J, Geerlings P, Gidopoulos N, Gill PMW, Gori-Giorgi P, Görling A, Gould T, Grimme S, Gritsenko O, Jensen HJA, Johnson ER, Jones RO, Kaupp M, Köster AM, Kronik L, Krylov AI, Kvaal S, Laestadius A, Levy M, Lewin M, Liu S, Loos PF, Maitra NT, Neese F, Perdew JP, Pernal K, Pernot P, Piecuch P, Rebolini E, Reining L, Romaniello P, Ruzsinszky A, Salahub DR, Scheffler M, Schwerdtfeger P, Staroverov VN, Sun J, Tellgren E, Tozer DJ, Trickey SB, Ullrich CA, Vela A, Vignale G, Wesolowski TA, Xu X, Yang W. DFT exchange: sharing perspectives on the workhorse of quantum chemistry and materials science. Phys Chem Chem Phys 2022; 24:28700-28781. [PMID: 36269074 PMCID: PMC9728646 DOI: 10.1039/d2cp02827a] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 08/09/2022] [Indexed: 12/13/2022]
Abstract
In this paper, the history, present status, and future of density-functional theory (DFT) is informally reviewed and discussed by 70 workers in the field, including molecular scientists, materials scientists, method developers and practitioners. The format of the paper is that of a roundtable discussion, in which the participants express and exchange views on DFT in the form of 302 individual contributions, formulated as responses to a preset list of 26 questions. Supported by a bibliography of 777 entries, the paper represents a broad snapshot of DFT, anno 2022.
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Recio P, Alessandrini S, Vanuzzo G, Pannacci G, Baggioli A, Marchione D, Caracciolo A, Murray VJ, Casavecchia P, Balucani N, Cavallotti C, Puzzarini C, Barone V. Intersystem crossing in the entrance channel of the reaction of O( 3P) with pyridine. Nat Chem 2022; 14:1405-1412. [PMID: 36175514 DOI: 10.1038/s41557-022-01047-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 08/25/2022] [Indexed: 01/04/2023]
Abstract
Two quantum effects can enable reactions to take place at energies below the barrier separating reactants from products: tunnelling and intersystem crossing between coupled potential energy surfaces. Here we show that intersystem crossing in the region between the pre-reactive complex and the reaction barrier can control the rate of bimolecular reactions for weakly coupled potential energy surfaces, even in the absence of heavy atoms. For O(3P) plus pyridine, a reaction relevant to combustion, astrochemistry and biochemistry, crossed-beam experiments indicate that the dominant products are pyrrole and CO, obtained through a spin-forbidden ring-contraction mechanism. The experimental findings are interpreted-by high-level quantum-chemical calculations and statistical non-adiabatic computations of branching fractions-in terms of an efficient intersystem crossing occurring before the high entrance barrier for O-atom addition to the N-atom lone pair. At low to moderate temperatures, the computed reaction rates prove to be dominated by intersystem crossing.
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Falbo E, Fusè M, Lazzari F, Mancini G, Barone V. Integration of Quantum Chemistry, Statistical Mechanics, and Artificial Intelligence for Computational Spectroscopy: The UV-Vis Spectrum of TEMPO Radical in Different Solvents. J Chem Theory Comput 2022; 18:6203-6216. [PMID: 36166322 PMCID: PMC9558374 DOI: 10.1021/acs.jctc.2c00654] [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: 11/30/2022]
Abstract
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The ongoing integration of quantum chemistry, statistical
mechanics,
and artificial intelligence is paving the route toward more effective
and accurate strategies for the investigation of the spectroscopic
properties of medium-to-large size chromophores in condensed phases.
In this context we are developing a novel workflow aimed at improving
the generality, reliability, and ease of use of the available computational
tools. In this paper we report our latest developments with specific
reference to unsupervised atomistic simulations employing non periodic
boundary conditions (NPBC) followed by clustering of the trajectories
employing optimized feature spaces. Next accurate variational computations
are performed for a representative point of each cluster, whereas
intracluster fluctuations are taken into account by a cheap yet reliable
perturbative approach. A number of methodological improvements have
been introduced including, e.g., more realistic reaction field effects
at the outer boundary of the simulation sphere, automatic definition
of the feature space by continuous perception of solute–solvent
interactions, full account of polarization and charge transfer in
the first solvation shell, and inclusion of vibronic contributions.
After its validation, this new approach has been applied to the challenging
case of solvatochromic effects on the UV–vis spectra of a prototypical
nitroxide radical (TEMPO) in different solvents. The reliability,
effectiveness, and robustness of the new platform is demonstrated
by the remarkable agreement with experiment of the results obtained
through an unsupervised approach characterized by a strongly reduced
computational cost as compared to that of conventional quantum mechanics
and molecular mechanics models without any accuracy reduction.
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León I, Fusè M, Alonso ER, Mata S, Mancini G, Puzzarini C, Alonso JL, Barone V. Unbiased disentanglement of conformational baths with the help of microwave spectroscopy, quantum chemistry and artificial intelligence: the puzzling case of homocysteine. J Chem Phys 2022; 157:074107. [DOI: 10.1063/5.0102841] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
An integrated experimental-computational strategy for the accurate characterization of the conformational landscape of flexible biomolecule building blocks is proposed. This is based on the combination of rotational spectroscopy with quantum-chemical computations guided by artificial intelligence tools. The first step of the strategy is the conformer search and relative stability evaluation performed by means of an evolutionary algorithm. In this step, last generation semiempirical methods are exploited together with hybrid and double-hybrid density functionals. Next, the barriers ruling the interconversion between the low-lying conformers are evaluated in order to unravel possible fast relaxation paths. The relative stabilities and spectroscopic parameters of the ``surviving' conformers are then refined using state-of-the-art composite schemes. The reliability of the computational procedure is further improved by the inclusion of vibrational and thermal effects. The final step of the strategy is the comparison between experiment and theory without any ad hoc adjustment, which allows an unbiased assignment of the spectroscopic features in terms of different conformers and their spectroscopic parameters. The proposed approach has been tested and validated for homocysteine, a highly flexible non-proteinogenic alpha-amino acid. The synergism of the integrated strategy allowed the characterization of five conformers stabilized by bifurcated N-H-O=C hydrogen bonds, together with an additional conformer involving a more conventional HNH-O hydrogen bond. The stability order estimated from the experimental intensities as well as the number and type of conformers observed in the gas phase are in full agreement with the theoretical predictions. Analogously, a good match has been found for the spectroscopic parameters.
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Salta Z, Vega-Teijido M, Katz A, Tasinato N, Barone V, Ventura ON. Dipolar 1,3-cycloaddition of thioformaldehyde S-methylide (CH 2 SCH 2 ) to ethylene and acetylene. A comparison with (valence) isoelectronic O 3 , SO 2 , CH 2 OO and CH 2 SO. J Comput Chem 2022; 43:1420-1433. [PMID: 35662073 DOI: 10.1002/jcc.26946] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/17/2022] [Accepted: 05/17/2022] [Indexed: 11/08/2022]
Abstract
Methods rooted in the density functional theory and in the coupled cluster ansatz were employed to investigate the cycloaddition reactions to ethylene and acetylene of 1,3-dipolar species including ozone and the derivatives issued from replacement of the central oxygen atom by the valence-isoelectronic sulfur atom, and/or of one or both terminal oxygen atoms by the isoelectronic CH2 group. This gives rise to five different 1,3-dipolar compounds, namely ozone itself (O3 ), sulfur dioxide (SO2 ), the simplest Criegee intermediate (CH2 OO), sulfine (CH2 SO), and thioformaldehyde S-methylide (CH2 SCH2 , TSM). The experimental and accurate theoretical data available for some of those molecules were employed to assess the accuracy of two last-generation composite methods employing conventional or explicitly correlated post-Hartree-Fock contributions (jun-Cheap and SVECV-f12, respectively), which were then applied to investigate the reactivity of TSM. The energy barriers provided by both composite methods are very close (the average values for the two composite methods are 7.1 and 8.3 kcal mol-1 for the addition to ethylene and acetylene, respectively) and comparable to those ruling the corresponding additions of ozone (4.0 and 7.7 kcal mol-1 , respectively). These and other evidences strongly suggest that, at least in the case of cycloadditions, the reactivity of TSM is similar to that of O3 and very different from that of SO2 .
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Melli A, Melosso M, Lengsfeld KG, Bizzocchi L, Rivilla VM, Dore L, Barone V, Grabow JU, Puzzarini C. Spectroscopic Characterization of 3-Aminoisoxazole, a Prebiotic Precursor of Ribonucleotides. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27103278. [PMID: 35630755 PMCID: PMC9147597 DOI: 10.3390/molecules27103278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 05/16/2022] [Accepted: 05/18/2022] [Indexed: 11/17/2022]
Abstract
The processes and reactions that led to the formation of the first biomolecules on Earth play a key role in the highly debated theme of the origin of life. Whether the first chemical building blocks were generated on Earth (endogenous synthesis) or brought from space (exogenous delivery) is still unanswered. The detection of complex organic molecules in the interstellar medium provides valuable support to the latter hypothesis. To gather more insight, here we provide the astronomers with accurate rotational frequencies to guide the interstellar search of 3-aminoisoxazole, which has been recently envisaged as a key reactive species in the scenario of the so-called RNA-world hypothesis. Relying on an accurate computational characterization, we were able to register and analyze the rotational spectrum of 3-aminoisoxazole in the 6–24 GHz and 80–320 GHz frequency ranges for the first time, exploiting a Fourier-transform microwave spectrometer and a frequency-modulated millimeter/sub-millimeter spectrometer, respectively. Due to the inversion motion of the −NH2 group, two states arise, and both of them were characterized, with more than 1300 lines being assigned. Although the fit statistics were affected by an evident Coriolis interaction, we were able to produce accurate line catalogs for astronomical observations of 3-aminoisoxazole.
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Baiano C, Lupi J, Barone V, Tasinato N. Gliding on Ice in Search of Accurate and Cost-Effective Computational Methods for Astrochemistry on Grains: The Puzzling Case of the HCN Isomerization. J Chem Theory Comput 2022; 18:3111-3121. [PMID: 35446575 PMCID: PMC9097295 DOI: 10.1021/acs.jctc.1c01252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Indexed: 11/28/2022]
Abstract
The isomerization of hydrogen cyanide to hydrogen isocyanide on icy grain surfaces is investigated by an accurate composite method (jun-Cheap) rooted in the coupled cluster ansatz and by density functional approaches. After benchmarking density functional predictions of both geometries and reaction energies against jun-Cheap results for the relatively small model system HCN···(H2O)2, the best performing DFT methods are selected. A large cluster containing 20 water molecules is then employed within a QM/QM' approach to include a realistic environment mimicking the surface of icy grains. Our results indicate that four water molecules are directly involved in a proton relay mechanism, which strongly reduces the activation energy with respect to the direct hydrogen transfer occurring in the isolated molecule. Further extension of the size of the cluster up to 192 water molecules in the framework of a three-layer QM/QM'/MM model has a negligible effect on the energy barrier ruling the isomerization. Computation of reaction rates by the transition state theory indicates that on icy surfaces, the isomerization of HNC to HCN could occur quite easily even at low temperatures thanks to the reduced activation energy that can be effectively overcome by tunneling.
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Sallustio F, Curci C, Teresa Cimmarusti M, Picerno A, Giannuzzi F, De Palma G, Sivo C, Annese F, Fonto G, Tafuri S, Cara I, Barone V, Stasi A, Pesce F, DI Leo V, Gesualdo L. FC073: An Epigenetically Driven Mechanism Triggered by Viral and Bacterial RNA Regulates the IL-6 Levels in IGA Nephropathy. Nephrol Dial Transplant 2022. [PMCID: PMC9383845 DOI: 10.1093/ndt/gfac113.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND AND AIMS Several models have been proposed to describe the pathogenesis of Immunoglobulin A nephropathy (IgAN) and, among them, the multihit model where the gut-microbiota may play an important role. These models explain the pathogenesis of IgAN caused by the production of aberrant IgA, but it is believed that further predisposing factors are present, including immunological, genetic, environmental or nutritional factors. Recently, the role of IL-6 in IgAN pathogenesis is becoming increasingly important. It is essential for the deposition of glomerular immunoglobulin A and the development of renal disease in Cd37-deficient mice, although the pathogenetic mechanisms that determine its increase are not well known. A possible hypothesis emerges from our recent work on genome-wide DNA methylation screening in patients with IgAN, which identified, among other findings, a hypermethylated region comprising Vault 2–1 RNA (VTRNA2-1), a non-RNA coding also known as a precursor of miR-886 (pre-mi-RNA). Consistently, VTRNA2-1 expression was found downregulated in IgAN patients. Here we studied the involvement of the VTRNA2-1/PKR/CREB/IL-6 pathway in IgAN. METHOD Total RNA were isolated from PBMCs of IgAN patients, transplanted IgAN patients (TP-IgAN), non-IgAN transplanted patients (TP) and healthy subjects (HS). VTRNA2-1, CREB and PKR transcripts were evaluated by RT-PCR. Total and phosphorylated PKR, CREB and Il-6 proteins were evaluated by ELISA. Poly (I: C), a synthetic analogue of dsRNA and Pfizer-BioNTech COVID-19 COMIRNATY vaccine were used to transfect patient PBMCs. PKR inhibitor imoxin (C16) 1 µM was used to stimulate patient PBMCs. RESULTS Here we confirm that VTRNA2-1 transcript was down-regulated in native and transplanted IgAN subjects compared to HS and non IgAN transplanted patients, with a decrease of 30- and 100-folds, respectively (P < 0.05, and P < 0.0001). IgAN patients with downregulated VTRNA2-1 showed a PKR overactivation (fold increase of phosphorilation of 2.6- in IgAN and 2-folds in TP-IgAN patients; P < 0.05), coherently with the role played by VTRNA2-1 that binds to PKR and inhibits its phosphorylation. Then, we found that PKR causes the activation of CREB, a classical cAMP-inducible CRE-binding factor (fold increase of phosphorilation of 3- in IgAN and 2.67-folds in TP-IgAN patients; P < 0.01). CREB, interacting with a region of the IL-6 promoter, led to IL-6 production. Indeed, in IgAN patients we showed a IL-6 mean increase to 120 pg/mL compared to the respective controls (P < 0.05). Moreover, the IL-6 levels correlated with CREB and PKR phosphorylation (r = 0.97; P = 0.0006 and r = 0.89; P = 0.0064, respectively, for IgAN and TP-IgAN patients). Since PKR is normally activated by bacterial and viral RNA, we hypothesized that these microorganisms can further activate the PKR/CREB/IL-6 pathway leading to an excess of IL-6 production. This may explain both the high levels of IL-6, and infection involvement in the disease, and cases of IgAN associated with COVID-19 infection or with COVID-19 RNA-vaccination, and recent data showing microbiota involvement in IgAN. Effectively, we found that IgAN PMBCs stimulated with RNA poly(I: C) or the COVID-19 RNA-vaccine showed a significant increase in IL-6 levels compared to not-stimulated PBMCs (P < 0.05), supporting the pathogentic role played by viral RNA in IgAN pathogenesis and explaining the cases of IgAN patients developing episodes of macrohematuria after a COVID-19 infection or vaccination. Finally, we showed that the IL-6 secretion can be reduced by the PKR inhibitor imoxin (fold decrease of 5-folds in IgAN and TP-IgAN patients; P < 0.05). CONCLUSION In conclusion, the discovery of the upregulated VTRNA2-1/PKR/CREB/IL-6 pathway in IgAN patients may provide a new pathogenic mechanism in IgAN and may be useful for the development of novel therapeutic approaches, likely by modulating the VTRNA2-1 methylation level in IgAN patients.
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Ceselin G, Salta Z, Bloino J, Tasinato N, Barone V. Accurate Quantum Chemical Spectroscopic Characterization of Glycolic Acid: A Route Toward its Astrophysical Detection. J Phys Chem A 2022; 126:2373-2387. [PMID: 35384666 PMCID: PMC9036519 DOI: 10.1021/acs.jpca.2c01419] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
The first step to
shed light on the abiotic synthesis of biochemical
building blocks, and their further evolution toward biological systems,
is the detection of the relevant species in astronomical environments,
including earthlike planets. To this end, the species of interest
need to be accurately characterized from structural, energetic, and
spectroscopic viewpoints. This task is particularly challenging when
dealing with flexible systems, whose spectroscopic signature is ruled
by the interplay of small- and large-amplitude motions (SAMs and LAMs,
respectively) and is further tuned by the conformational equilibrium.
In such instances, quantum chemical (QC) calculations represent an
invaluable tool for assisting the interpretation of laboratory measurements
or even observations. In the present work, the role of QC results
is illustrated with reference to glycolic acid (CH2OHCOOH),
a molecule involved in photosynthesis and plant respiration and a
precursor of oxalate in humans, which has been detected in the Murchison
meteorite but not yet in the interstellar medium or in planetary atmospheres.
In particular, the equilibrium structure of the lowest-energy conformer
is derived by employing the so-called semiexperimental approach. Then,
accurate yet cost-effective QC calculations relying on composite post-Hartree–Fock
schemes and hybrid coupled-cluster/density functional theory approaches
are used to predict the structural and ro-vibrational spectroscopic
properties of the different conformers within the framework of the
second-order vibrational perturbation theory. A purposely tailored
discrete variable representation anharmonic approach is used to treat
the LAMs related to internal rotations. The computed spectroscopic
data, particularly those in the infrared region, complement the available
experimental investigations, thus enhancing the possibility of an
astronomical detection of this molecule.
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Barone V, Carnimeo I, Mancini G, Pagliai M. Development, Validation, and Pilot Application of a Generalized Fluctuating Charge Model for Computational Spectroscopy in Solution. ACS OMEGA 2022; 7:13382-13394. [PMID: 35474835 PMCID: PMC9026056 DOI: 10.1021/acsomega.2c01110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 03/23/2022] [Indexed: 06/14/2023]
Abstract
A general approach enforcing nonperiodic boundary conditions for the computation of spectroscopic properties in solution has been improved including an effective description of charge-transfer contributions and coordination number adjustment for explicit solvent molecules. Both contributions are obtained from a continuous description of intermolecular hydrogen bonds, which has been employed also for an effective clustering of molecular dynamics trajectories. Fine tuning of the model has been performed for several water clusters, and then its efficiency and reliability have been demonstrated by computing the absorption spectra of different creatinine tautomers in aqueous solution.
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Mancini G, Fusè M, Lipparini F, Nottoli M, Scalmani G, Barone V. Molecular Dynamics Simulations Enforcing Nonperiodic Boundary Conditions: New Developments and Application to the Solvent Shifts of Nitroxide Magnetic Parameters. J Chem Theory Comput 2022; 18:2479-2493. [PMID: 35257572 PMCID: PMC9009096 DOI: 10.1021/acs.jctc.2c00046] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
![]()
Multiscale methods
combining quantum mechanics and molecular mechanics
(QM/MM) have become the most suitable and effective strategies for
the investigation of the spectroscopic properties of medium-to-large
size chromophores in condensed phases. In this context, we are developing
a novel workflow aimed at improving the generality, reliability, and
ease of use of the available computational tools. In this paper, we
report our latest developments with specific reference to a general
protocol based on atomistic simulations, carried out under nonperiodic
boundary conditions (NPBC). In particular, we add to our in house
MD engine a new efficient treatment of mean field electrostatic contributions
to energy and forces, together with the capability of performing the
simulations either in the canonical (NVT) or in the
isothermal–isobaric (NPT) ensemble. Next,
we provide convincing evidence that the NBPC approach enhanced by
specific tweaks for rigid body propagation, allows for the simulation
of solute–solvent systems with a minimum number of degrees
of freedom and large integration time step. After its validation,
this new approach is applied to the challenging case of solvatochromic
effects on the electron paramagnetic resonance (EPR) spectrum of a
prototypical nitroxide radical. To this end, we propose and validate
also an automated protocol to extract and weight simulation snapshots,
making use of a continuous description of the strength of solute–solvent
hydrogen bridges. While further developments are being worked on,
the effectiveness of our approach, even in its present form, is demonstrated
by the accuracy of the results obtained through an unsupervised approach
characterized by a strongly reduced computational cost as compared
to that of conventional QM/MM models, without any appreciable deterioration
of accuracy.
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Melosso M, Bizzocchi L, Gazzeh H, Tonolo F, Guillemin JC, Alessandrini S, Rivilla VM, Dore L, Barone V, Puzzarini C. Gas-phase identification of ( Z)-1,2-ethenediol, a key prebiotic intermediate in the formose reaction. Chem Commun (Camb) 2022; 58:2750-2753. [PMID: 35119446 DOI: 10.1039/d1cc06919e] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Prebiotic sugars are thought to be formed on primitive Earth by the formose reaction. However, their formation is not fully understood and it is plausible that key intermediates could have formed in extraterrestrial environments and subsequently delivered on early Earth by cometary bodies. 1,2-Ethenediol, the enol form of glycolaldehyde, represents a highly reactive intermediate of the formose reaction and is likely detectable in the interstellar medium. Here, we report the identification and first characterization of (Z)-1,2-ethenediol by means of rotational spectroscopy. The title compound has been produced in the gas phase by flash vacuum pyrolysis of bis-exo-5-norbornene-2,3-diol at 750 °C, through a retro-Diels-Alder reaction. The spectral analysis was guided by high-level quantum-chemical calculations, which predicted spectroscopic parameters in very good agreement with the experiment. Our study provides accurate spectral data to be used for searches of (Z)-1,2-ethenediol in the interstellar space.
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Del Frate G, Macchiagodena M, Akhunzada MJ, D'Autilia F, Catte A, Bhattacharjee N, Barone V, Cardarelli F, Brancato G. Probing Liquid-Ordered and Disordered Phases in Lipid Model Membranes: A Combined Theoretical and Spectroscopic Study of a Fluorescent Molecular Rotor. J Phys Chem B 2022; 126:480-491. [PMID: 35001625 PMCID: PMC8785181 DOI: 10.1021/acs.jpcb.1c08324] [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: 11/30/2022]
Abstract
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An integrated theoretical/experimental
strategy has been applied
to the study of environmental effects on the spectroscopic parameters
of 4-(diphenylamino)phtalonitrile (DPAP), a fluorescent molecular
rotor. The computational part starts from the development of an effective
force field for the first excited electronic state of DPAP and proceeds
through molecular dynamics simulations in solvents of different polarities
toward the evaluation of Stokes shifts by quantum mechanics/molecular
mechanics (QM/MM) approaches. The trends of the computed results closely
parallel the available experimental results thus giving confidence
to the interpretation of new experimental studies of the photophysics
of DPAP in lipid bilayers. In this context, results show unambiguously
that both flexible dihedral angles and global rotations are significantly
retarded in a cholesterol/DPPC lipid matrix with respect to the DOPC
matrix, thus confirming the sensitivity of DPAP to probe different
environments and, therefore, its applicability as a probe for detecting
different structures and levels of plasma membrane organization.
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Li X, Spada L, Alessandrini S, Zheng Y, Lengsfeld KG, Grabow J, Feng G, Puzzarini C, Barone V. Gestapelt, nicht geklebt: Enthüllung der π→π*‐Wechselwirkung mithilfe des Benzofuran‐Formaldehyd‐Komplexes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202113737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Tonolo F, Bizzocchi L, Melosso M, Lique F, Dore L, Barone V, Puzzarini C. An improved study of HCO + and He system: Interaction potential, collisional relaxation, and pressure broadening. J Chem Phys 2021; 155:234306. [PMID: 34937352 DOI: 10.1063/5.0075929] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In light of its ubiquitous presence in the interstellar gas, the chemistry and reactivity of the HCO+ ion requires special attention. The availability of up-to-date collisional data between this ion and the most abundant perturbing species in the interstellar medium is a critical resource in order to derive reliable values of its molecular abundance from astronomical observations. This work intends to provide improved scattering parameters for the HCO+ and He collisional system. We have tested the accuracy of explicitly correlated coupled-cluster methods for mapping the short- and long-range multi-dimensional potential energy surface of atom-ion systems. A validation of the methodology employed for the calculation of the potential well has been obtained from the comparison with experimentally derived bound-state spectroscopic parameters. Finally, by solving the close-coupling scattering equations, we have derived the pressure broadening and shift coefficients for the first six rotational transitions of HCO+ as well as inelastic state-to-state transition rates up to j = 5 in the 5-100 K temperature interval.
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Biswas AD, Catte A, Mancini G, Barone V. Analysis of L-DOPA and droxidopa binding to human β 2-adrenergic receptor. Biophys J 2021; 120:5631-5643. [PMID: 34767786 PMCID: PMC8715240 DOI: 10.1016/j.bpj.2021.11.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/28/2021] [Accepted: 11/03/2021] [Indexed: 12/29/2022] Open
Abstract
Over the last two decades, an increasing number of studies has been devoted to a deeper understanding of the molecular process involved in the binding of various agonists and antagonists to active and inactive conformations of β2-adrenergic receptor (β2AR). The 3.2 Å x-ray crystal structure of human β2AR active state in combination with the endogenous low affinity agonist adrenaline offers an ideal starting structure for studying the binding of various catecholamines to adrenergic receptors. We show that molecular docking of levodopa (L-DOPA) and droxidopa into rigid and flexible β2AR models leads for both ligands to binding anchor sites comparable to those experimentally reported for adrenaline, namely D113/N312 and S203/S204/S207 side chains. Both ligands have a hydrogen bond network that is extremely similar to those of noradrenaline and dopamine. Interestingly, redocking neutral and protonated versions of adrenaline to rigid and flexible β2AR models results in binding poses that are more energetically stable and distinct from the x-ray crystal structure. Similarly, lowest energy conformations of noradrenaline and dopamine generated by docking into flexible β2AR models had binding free energies lower than those of best poses in rigid receptor models. Furthermore, our findings show that L-DOPA and droxidopa molecules have binding affinities comparable to those predicted for adrenaline, noradrenaline, and dopamine, which are consistent with previous experimental and computational findings and supported by the molecular dynamics simulations of β2AR-ligand complexes performed here.
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Barbosa N, Pagliai M, Sinha S, Barone V, Alfè D, Brancato G. Enhancing the Accuracy of Ab Initio Molecular Dynamics by Fine Tuning of Effective Two-Body Interactions: Acetonitrile as a Test Case. J Phys Chem A 2021; 125:10475-10484. [PMID: 34843249 DOI: 10.1021/acs.jpca.1c07576] [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
Grimme's dispersion-corrected density functional theory (DFT-D) methods have emerged among the most practical approaches to perform accurate quantum mechanical calculations on molecular systems ranging from small clusters to microscopic and mesoscopic samples, i.e., including hundreds or thousands of molecules. Moreover, DFT-D functionals can be easily integrated into popular ab initio molecular dynamics (MD) software packages to carry out first-principles condensed-phase simulations at an affordable computational cost. Here, starting from the well-established D3 version of the dispersion-correction term, we present a simple protocol to improve the accurate description of the intermolecular interactions of molecular clusters of growing size, considering acetonitrile as a test case. Optimization of the interaction energy was performed with reference to diffusion quantum Monte Carlo calculations, successfully reaching the same inherent accuracy of the latter (statistical error of ∼0.1 kcal/mol per molecule). The refined DFT-D3 model was then used to perform ab initio MD simulations of liquid acetonitrile, again showing significant improvements toward available experimental data with respect to the default correction.
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Barone V, Fusè M, Pinto SMV, Tasinato N. A Computational Journey across Nitroxide Radicals: From Structure to Spectroscopic Properties and Beyond. Molecules 2021; 26:molecules26237404. [PMID: 34885980 PMCID: PMC8659111 DOI: 10.3390/molecules26237404] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 11/25/2021] [Accepted: 12/02/2021] [Indexed: 11/17/2022] Open
Abstract
Nitroxide radicals are characterized by a long-lived open-shell electronic ground state and are strongly sensitive to the chemical environment, thus representing ideal spin probes and spin labels for paramagnetic biomolecules and materials. However, the interpretation of spectroscopic parameters in structural and dynamic terms requires the aid of accurate quantum chemical computations. In this paper we validate a computational model rooted into double-hybrid functionals and second order vibrational perturbation theory. Then, we provide reference quantum chemical results for the structures, vibrational frequencies and other spectroscopic features of a large panel of nitroxides of current biological and/or technological interest.
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Melli A, Tonolo F, Barone V, Puzzarini C. Extending the Applicability of the Semi-experimental Approach by Means of "Template Molecule" and "Linear Regression" Models on Top of DFT Computations. J Phys Chem A 2021; 125:9904-9916. [PMID: 34752702 PMCID: PMC8607424 DOI: 10.1021/acs.jpca.1c07828] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/20/2021] [Indexed: 11/28/2022]
Abstract
The accurate determination of equilibrium structures for isolated molecules plays a central role in the evaluation and interpretation of stereoelectronic, thermodynamic, and spectroscopic properties. For small semi-rigid systems, state-of-the-art quantum-chemical computations can rival the most sophisticated experimental results. For larger molecules, cheaper yet accurate approaches need to be defined. The double-hybrid rev-DSD-PBEP86 functional already delivers remarkable results that can be further improved by means of a "Lego brick" model. This is based on the idea that a molecular system can be seen as formed by different fragments (the "Lego bricks"), whose accurate semi-experimental (SE) equilibrium geometries are available. The template molecule (TM) approach can be used to account for the modifications occurring when going from the isolated fragment to the molecular system under investigation, with the linear regression (LR) model employed to correct the linkage between the different fragments. The resulting TM-SE_LR approach has been tested with respect to available SE equilibrium structures and rotational constants. Indeed, the latter parameters straightforwardly depend on the equilibrium geometry of the system under consideration. The main outcome of our study is the reliability, robustness, and accuracy of this novel approach. The molecular systems considered for benchmarking the TM-SE_LR scheme are those formally issued from addition/elimination reactions of nucleophilic unsaturated radicals (e.g., CN, C2H, and phenyl) to alkenes, imines, and aldehydes, whose rotational spectra have been investigated, but accurate structural determinations are not yet available.
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Lupi J, Alessandrini S, Puzzarini C, Barone V. junChS and junChS-F12 Models: Parameter-free Efficient yet Accurate Composite Schemes for Energies and Structures of Noncovalent Complexes. J Chem Theory Comput 2021; 17:6974-6992. [PMID: 34677974 DOI: 10.1021/acs.jctc.1c00869] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A recently developed model chemistry (denoted as junChS [Alessandrini, S.; et al. J. Chem. Theory Comput. 2020, 16, 988-1006]) has been extended to the employment of explicitly correlated (F12) methods. This led us to propose a family of effective, reliable, and parameter-free schemes for the computation of accurate interaction energies of molecular complexes ruled by noncovalent interactions. A thorough benchmark based on a wide range of interactions showed that the so-called junChS-F12 model, which employs cost-effective revDSD-PBEP86-D3(BJ) reference geometries, has an improved performance with respect to its conventional counterpart and outperforms well-known model chemistries. Without employing any empirical parameter and at an affordable computational cost, junChS-F12 reaches subchemical accuracy. Accurate characterizations of molecular complexes are usually limited to energetics. To take a step forward, the conventional and F12 composite schemes developed for interaction energies have been extended to structural determinations. A benchmark study demonstrated that the most effective option is to add MP2-F12 core-valence correlation corrections to fc-CCSD(T)-F12/jun-cc-pVTZ geometries without the need of recovering the basis set superposition error and the extrapolation to the complete basis set.
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