1
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Martin PD, Svensson B, Thomas DD, Stoll S. Trajectory-Based Simulation of EPR Spectra: Models of Rotational Motion for Spin Labels on Proteins. J Phys Chem B 2019; 123:10131-10141. [PMID: 31693365 DOI: 10.1021/acs.jpcb.9b02693] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Direct time-domain simulation of continuous-wave (CW) electron paramagnetic resonance (EPR) spectra from molecular dynamics (MD) trajectories has become increasingly popular, especially for proteins labeled with nitroxide spin labels. Due to the time-consuming nature of simulating adequately long MD trajectories, two approximate methods have been developed to reduce the MD-trajectory length required for modeling EPR spectra: hindered Brownian diffusion (HBD) and hidden Markov models (HMMs). Here, we assess the accuracy of these two approximate methods relative to direct simulations from MD trajectories for three spin-labeled protein systems (a simple helical peptide, a soluble protein, and a membrane protein) and two nitroxide spin labels with differing mobilities (R1 and 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC)). We find that the HMMs generally outperform HBD. Although R1 dynamics partially resembles hindered Brownian diffusion, HMMs accommodate the multiple dynamic time scales for the transitions between rotameric states of R1 that cannot be captured accurately by a HBD model. The MD trajectories of the TOAC-labeled proteins show that its dynamics closely resembles slow multisite exchange between twist-boat and chair ring puckering states. This motion is modeled well by HMM but not by HBD. All MD-trajectory data processing, stochastic trajectory simulations, and CW EPR spectral simulations are implemented in EasySpin, a free software package for MATLAB.
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Affiliation(s)
| | | | | | - Stefan Stoll
- Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States
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2
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Yang X, Rees RJ, Conway W, Puxty G, Yang Q, Winkler DA. Computational Modeling and Simulation of CO2 Capture by Aqueous Amines. Chem Rev 2017; 117:9524-9593. [PMID: 28517929 DOI: 10.1021/acs.chemrev.6b00662] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Xin Yang
- CSIRO Manufacturing, Bayview Avenue, Clayton 3169, Australia
- College
of Chemistry, Key Lab of Green Chemistry and Technology in Ministry
of Education, Sichuan University, Chengdu 610064, People’s Republic of China
| | - Robert J. Rees
- Data61
- CSIRO, Door 34 Goods
Shed, Village Street, Docklands VIC 3008, Australia
| | | | | | - Qi Yang
- CSIRO Manufacturing, Bayview Avenue, Clayton 3169, Australia
| | - David A. Winkler
- CSIRO Manufacturing, Bayview Avenue, Clayton 3169, Australia
- Monash Institute of Pharmaceutical Sciences, 392 Royal Parade, Parkville 3052, Australia
- Latrobe Institute for Molecular Science, Bundoora 3046, Australia
- School
of
Chemical and Physical Science, Flinders University, Bedford Park 5042, Australia
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3
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Salvadori A, Del Frate G, Pagliai M, Mancini G, Barone V. Immersive virtual reality in computational chemistry: Applications to the analysis of QM and MM data. INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY 2016; 116:1731-1746. [PMID: 27867214 PMCID: PMC5101850 DOI: 10.1002/qua.25207] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 06/21/2016] [Accepted: 06/24/2016] [Indexed: 05/31/2023]
Abstract
The role of Virtual Reality (VR) tools in molecular sciences is analyzed in this contribution through the presentation of the Caffeine software to the quantum chemistry community. Caffeine, developed at Scuola Normale Superiore, is specifically tailored for molecular representation and data visualization with VR systems, such as VR theaters and helmets. Usefulness and advantages that can be gained by exploiting VR are here reported, considering few examples specifically selected to illustrate different level of theory and molecular representation.
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Affiliation(s)
- Andrea Salvadori
- Scuola Normale Superiore Piazza dei Cavalieri 7 Pisa I-56126 Italy
| | | | - Marco Pagliai
- Scuola Normale Superiore Piazza dei Cavalieri 7 Pisa I-56126 Italy
| | - Giordano Mancini
- Scuola Normale Superiore Piazza dei Cavalieri 7 Pisa I-56126 Italy
| | - Vincenzo Barone
- Scuola Normale Superiore Piazza dei Cavalieri 7 Pisa I-56126 Italy
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4
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Teixeira LGD, Malavolta L, Bersanetti PA, Schreier S, Carmona AK, Nakaie CR. Paramagnetic bradykinin analogues as substrates for angiotensin I-converting enzyme: Pharmacological and conformation studies. Bioorg Chem 2016; 69:159-166. [PMID: 27837711 DOI: 10.1016/j.bioorg.2016.10.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/10/2016] [Accepted: 10/26/2016] [Indexed: 11/27/2022]
Abstract
This study uses EPR, CD, and fluorescence spectroscopy to examine the structure of bradykinin (BK) analogues attaching the paramagnetic amino acid-type Toac (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) at positions 0, 3, 7, and 9. The data were correlated with the potencies in muscle contractile experiments and the substrate properties towards the angiotensin I-converting enzyme (ACE). A study of the biological activities in guinea pig ileum and rat uterus indicated that only Toac0-BK partially maintained its native biological potency among the tested peptides. This and its counterpart, Toac3-BK, maintained the ability to act as ACE substrates. These results indicate that peptides bearing Toac probe far from the ACE cleavage sites were more susceptible to hydrolysis by ACE. The results also emphasize the existence of a finer control for BK-receptor interaction than for BK binding at the catalytic site of this metallodipetidase. The kinetic kcat/Km values decreased from 202.7 to 38.9μM-1min-1 for BK and Toac3-BK, respectively. EPR, CD, and fluorescence experiments reveal a direct relationship between the structure and activity of these paramagnetic peptides. In contrast to the turn-folded structures of the Toac-internally labeled peptides, more extended conformations were displayed by N- or C-terminally Toac-labeled analogues. Lastly, this work supports the feasibility of monitoring the progress of the ACE-hydrolytic process of Toac-attached peptides by examining time-dependent EPR spectral variations.
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Affiliation(s)
- Luis Gustavo Deus Teixeira
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, 04044-020 Sao Paulo, SP, Brazil
| | - Luciana Malavolta
- Department of Physiological Sciences, Santa Casa de Sao Paulo, School of Medical Sciences, 01221-020 Sao Paulo, SP, Brazil
| | | | - Shirley Schreier
- Department of Biochemistry, Institute of Chemistry, Universidade de Sao Paulo, 05513-970 Sao Paulo, SP, Brazil
| | - Adriana K Carmona
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, 04044-020 Sao Paulo, SP, Brazil
| | - Clovis R Nakaie
- Department of Biophysics, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, 04044-020 Sao Paulo, SP, Brazil.
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5
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Pérez-Cruz F, Villamena FA, Zapata-Torres G, Das A, Headley CA, Quezada E, Lopez-Alarcon C, Olea-Azar C. Selected hydroxycoumarins as antioxidants in cells: physicochemical and reactive oxygen species scavenging studies. J PHYS ORG CHEM 2013. [DOI: 10.1002/poc.3155] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Fernanda Pérez-Cruz
- Free Radical and Antioxidants Laboratory, Faculty of Chemical and Pharmaceutical Sciences; University of Chile; Santiago Chile
| | - Frederick A. Villamena
- Department of Pharmacology, Davis Heart and Lung Research Institute, College of Medicine; The Ohio State University; Columbus OH 43210 USA
| | - Gerald Zapata-Torres
- Molecular Graphics Unit, Faculty of Chemical and Pharmaceutical Sciences; University of Chile; Santiago Chile
| | - Amlan Das
- Department of Pharmacology, Davis Heart and Lung Research Institute, College of Medicine; The Ohio State University; Columbus OH 43210 USA
| | - Colwyn A. Headley
- Department of Pharmacology, Davis Heart and Lung Research Institute, College of Medicine; The Ohio State University; Columbus OH 43210 USA
| | - Elias Quezada
- Departamento de Química Orgánica, Facultad de Farmacia; Universidad de Santiago de Compostela; 15782 Santiago de Compostela Spain
| | | | - Claudio Olea-Azar
- Free Radical and Antioxidants Laboratory, Faculty of Chemical and Pharmaceutical Sciences; University of Chile; Santiago Chile
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6
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Dihydropyridine-fused and pyridine-fused coumarins: Reduction on a glassy carbon electrode in dimethylformamide. Electrochim Acta 2012. [DOI: 10.1016/j.electacta.2012.08.088] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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The spin label amino acid TOAC and its uses in studies of peptides: chemical, physicochemical, spectroscopic, and conformational aspects. Biophys Rev 2012; 4:45-66. [PMID: 22347893 PMCID: PMC3271205 DOI: 10.1007/s12551-011-0064-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 12/20/2011] [Indexed: 01/21/2023] Open
Abstract
We review work on the paramagnetic amino acid 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid, TOAC, and its applications in studies of peptides and peptide synthesis. TOAC was the first spin label probe incorporated in peptides by means of a peptide bond. In view of the rigid character of this cyclic molecule and its attachment to the peptide backbone via a peptide bond, TOAC incorporation has been very useful to analyze backbone dynamics and peptide secondary structure. Many of these studies were performed making use of EPR spectroscopy, but other physical techniques, such as X-ray crystallography, CD, fluorescence, NMR, and FT-IR, have been employed. The use of double-labeled synthetic peptides has allowed the investigation of their secondary structure. A large number of studies have focused on the interaction of peptides, both synthetic and biologically active, with membranes. In the latter case, work has been reported on ligands and fragments of GPCR, host defense peptides, phospholamban, and β-amyloid. EPR studies of macroscopically aligned samples have provided information on the orientation of peptides in membranes. More recent studies have focused on peptide–protein and peptide–nucleic acid interactions. Moreover, TOAC has been shown to be a valuable probe for paramagnetic relaxation enhancement NMR studies of the interaction of labeled peptides with proteins. The growth of the number of TOAC-related publications suggests that this unnatural amino acid will find increasing applications in the future.
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8
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Grubišić S, Brancato G, Pedone A, Barone V. Extension of the AMBER force field to cyclic α,α dialkylated peptides. Phys Chem Chem Phys 2012; 14:15308-20. [DOI: 10.1039/c2cp42713c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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9
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Rinkevicius Z, Frecuş B, Murugan NA, Vahtras O, Kongsted J, Ågren H. Encapsulation Influence on EPR Parameters of Spin-Labels: 2,2,6,6-Tetramethyl-4-methoxypiperidine-1-oxyl in Cucurbit[8]uril. J Chem Theory Comput 2011; 8:257-63. [DOI: 10.1021/ct200816z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Zilvinas Rinkevicius
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
- Swedish e-Science Research Center (SeRC), Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - Bogdan Frecuş
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - N. Arul Murugan
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Olav Vahtras
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Jacob Kongsted
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Hans Ågren
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
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10
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Stoller S, Sicoli G, Baranova TY, Bennati M, Diederichsen U. TOPP: A Novel Nitroxide-Labeled Amino Acid for EPR Distance Measurements. Angew Chem Int Ed Engl 2011; 50:9743-6. [DOI: 10.1002/anie.201103315] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2011] [Indexed: 11/08/2022]
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11
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Rinkevicius Z, Murugan NA, Kongsted J, Frecuş B, Steindal AH, Ågren H. Density Functional Restricted–Unrestricted/Molecular Mechanics Theory for Hyperfine Coupling Constants of Molecules in Solution. J Chem Theory Comput 2011; 7:3261-71. [DOI: 10.1021/ct2003572] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Zilvinas Rinkevicius
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
- Swedish e-Science Research Center (SeRC), Royal Institute of Technology, SE-100 44 Stockholm, Sweden
| | - N. Arul Murugan
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Jacob Kongsted
- Department of Physics and Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark
| | - Bogdan Frecuş
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Arnfinn Hykkerud Steindal
- Centre of Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø, N-9037 Tromsø, Norway
| | - Hans Ågren
- Department of Theoretical Chemistry & Biology, School of Biotechnology, Royal Institute of Technology, SE-106 91 Stockholm, Sweden
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12
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Aguilera-Venegas B, Olea-Azar C, Norambuena E, Arán VJ, Mendizábal F, Lapier M, Maya JD, Kemmerling U, López-Muñoz R. ESR, electrochemical, molecular modeling and biological evaluation of 4-substituted and 1,4-disubstituted 7-nitroquinoxalin-2-ones as potential anti-Trypanosoma cruzi agents. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2011; 78:1004-1012. [PMID: 21239218 DOI: 10.1016/j.saa.2010.12.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 10/28/2010] [Accepted: 12/09/2010] [Indexed: 05/30/2023]
Abstract
Electrochemical and ESR studies were carried out in this work with the aim of characterizing the reduction mechanisms of 4-substituted and 1,4-disubstituted 7-nitroquinoxalin-2-ones by means of cyclic voltammetry in DMSO as aprotic solvent. Two reduction mechanisms were found for these compounds: the first, for compounds bearing a labile hydrogen by following a self-protonation mechanism (ECE steps), and the second, for compounds without labile hydrogen, based on a purely electrochemical reduction mechanism (typical of nitroheterocycles). The electrochemical results were corroborated using ESR spectroscopy allowing us to propose the hyperfine splitting pattern of the nitro-radical, which was later corroborated by the ESR simulation spectra. All these compounds were assayed as growth inhibitors against Trypanosoma cruzi: first, on the non-proliferative (and infective) form of the parasite (trypomastigote stage), and then, the ones that displayed activity, were assayed on the non-infective form (epimastigote stage). Thus, we found four new compounds highly active against T. cruzi. Finally, molecular modeling studies suggest the inhibition of the trypanothione reductase like one of the possible mechanisms involved in the trypanocidal action.
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Affiliation(s)
- Benjamín Aguilera-Venegas
- Departamento de Química Inorgánica y Analítica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
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13
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Revilla-López G, Torras J, Curcó D, Casanovas J, Calaza MI, Zanuy D, Jiménez AI, Cativiela C, Nussinov R, Grodzinski P, Alemán C. NCAD, a database integrating the intrinsic conformational preferences of non-coded amino acids. J Phys Chem B 2010; 114:7413-22. [PMID: 20455555 PMCID: PMC2896893 DOI: 10.1021/jp102092m] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Peptides and proteins find an ever-increasing number of applications in the biomedical and materials engineering fields. The use of non-proteinogenic amino acids endowed with diverse physicochemical and structural features opens the possibility to design proteins and peptides with novel properties and functions. Moreover, non-proteinogenic residues are particularly useful to control the three-dimensional arrangement of peptidic chains, which is a crucial issue for most applications. However, information regarding such amino acids--also called non-coded, non-canonical, or non-standard--is usually scattered among publications specialized in quite diverse fields as well as in patents. Making all these data useful to the scientific community requires new tools and a framework for their assembly and coherent organization. We have successfully compiled, organized, and built a database (NCAD, Non-Coded Amino acids Database) containing information about the intrinsic conformational preferences of non-proteinogenic residues determined by quantum mechanical calculations, as well as bibliographic information about their synthesis, physical and spectroscopic characterization, conformational propensities established experimentally, and applications. The architecture of the database is presented in this work together with the first family of non-coded residues included, namely, alpha-tetrasubstituted alpha-amino acids. Furthermore, the NCAD usefulness is demonstrated through a test-case application example.
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Affiliation(s)
- Guillem Revilla-López
- Departament d’Enginyeria Química, E. T. S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain
| | - Juan Torras
- Departament d’Enginyeria Química, EUETII, Universitat Politècnica de Catalunya, Pça Rei 15, Igualada 08700, Spain
| | - David Curcó
- Departament d’Enginyeria Química, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1, Barcelona E-08028, Spain
| | - Jordi Casanovas
- Departament de Química, Escola Politècnica Superior, Universitat de Lleida, c/ Jaume II n°69, Lleida E-25001, Spain
| | - M. Isabel Calaza
- Departamento de Química Orgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza – CSIC, 50009 Zaragoza, Spain
| | - David Zanuy
- Departament d’Enginyeria Química, E. T. S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain
| | - Ana I. Jiménez
- Departamento de Química Orgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza – CSIC, 50009 Zaragoza, Spain
| | - Carlos Cativiela
- Departamento de Química Orgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza – CSIC, 50009 Zaragoza, Spain
| | - Ruth Nussinov
- Basic Science Program, SAIC-Frederick, Inc. Center for Cancer Research Nanobiology Program, NCI, Frederick, MD 21702, USA
- Department of Human Genetics Sackler, Medical School, Tel Aviv University, Tel Aviv 69978, Israel
| | - Piotr Grodzinski
- Alliance for Nanotechnology in Cancer, National Cancer Institute, Bethesda, MD 20892, USA
| | - Carlos Alemán
- Departament d’Enginyeria Química, E. T. S. d’Enginyeria Industrial de Barcelona, Universitat Politècnica de Catalunya, Diagonal 647, 08028 Barcelona, Spain
- Center for Research in Nano-Engineering, Universitat Politècnica de Catalunya, Campus Sud, Edifici C’, C/Pasqual i Vila s/n, Barcelona E-08028, Spain
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14
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Lindfors HE, de Koning PE, Drijfhout JW, Venezia B, Ubbink M. Mobility of TOAC spin-labelled peptides binding to the Src SH3 domain studied by paramagnetic NMR. JOURNAL OF BIOMOLECULAR NMR 2008; 41:157-67. [PMID: 18560762 PMCID: PMC2480485 DOI: 10.1007/s10858-008-9248-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2008] [Accepted: 05/13/2008] [Indexed: 05/15/2023]
Abstract
Paramagnetic relaxation enhancement provides a tool for studying the dynamics as well as the structure of macromolecular complexes. The application of side-chain coupled spin-labels is limited by the mobility of the free radical. The cyclic, rigid amino acid spin-label TOAC (2,2,6,6-Tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid), which can be incorporated straightforwardly by peptide synthesis, provides an attractive alternative. In this study, TOAC was incorporated into a peptide derived from focal adhesion kinase (FAK), and the interaction of the peptide with the Src homology 3 (SH3) domain of Src kinase was studied, using paramagnetic NMR. Placing TOAC within the binding motif of the peptide has a considerable effect on the peptide-protein binding, lowering the affinity substantially. When the TOAC is positioned just outside the binding motif, the binding constant remains nearly unaffected. Although the SH3 domain binds weakly and transiently to proline-rich peptides from FAK, the interaction is not very dynamic and the relative position of the spin-label to the protein is well-defined. It is concluded that TOAC can be used to generate reliable paramagnetic NMR restraints.
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Affiliation(s)
- Hanna E. Lindfors
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Peter E. de Koning
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Centre, Leiden, The Netherlands
| | - Jan Wouter Drijfhout
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Centre, Leiden, The Netherlands
| | - Brigida Venezia
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Marcellus Ubbink
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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15
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Carlotto S, Cimino P, Zerbetto M, Franco L, Corvaja C, Crisma M, Formaggio F, Toniolo C, Polimeno A, Barone V. Unraveling Solvent-Driven Equilibria between α- and 310-Helices through an Integrated Spin Labeling and Computational Approach. J Am Chem Soc 2007; 129:11248-58. [PMID: 17705490 DOI: 10.1021/ja073516s] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work we present an effective and flexible computational approach, which is the result of an ongoing development in our groups, allowing the complete a priori simulation of the ESR spectra of complex systems in solution. The usefulness and reliability of the method are demonstrated on the very demanding playground represented by the tuning of the equilibrium between 3(10)- and alpha-helices of polypeptides by different solvents. The starting point is the good agreement between computed and X-ray diffraction structures for the 3(10)-helix adopted by the double spin-labelled heptapeptide Fmoc-(Aib-Aib-TOAC)2-Aib-OMe. Next, density functional computations, including dispersion interactions and bulk solvent effects, suggest another energy minimum corresponding to an alpha-helix in polar solvents, which, eventually, becomes the most stable structure. Computation of magnetic and diffusion tensors provides the basic ingredients for the building of complete spectra by methods rooted in the Stochastic Liouville Equation (SLE). The remarkable agreement between computed and experimental spectra at different temperatures allowed us to identify helical structures in the various solvents. The generality of the computational strategy and its implementation in effective and user-friendly computer codes pave the route toward systematic applications in the field of biomolecules and other complex systems.
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Affiliation(s)
- Silvia Carlotto
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, I-35131 Padova, Italy
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16
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de Deus Teixeira LG, Bersanetti PA, Schreier S, Carmona AK, Nakaie CR. Analogues containing the paramagnetic amino acid TOAC as substrates for angiotensin I-converting enzyme. FEBS Lett 2007; 581:2411-5. [PMID: 17485083 DOI: 10.1016/j.febslet.2007.04.058] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2007] [Revised: 03/26/2007] [Accepted: 04/13/2007] [Indexed: 01/02/2023]
Abstract
The angiotensin I-converting enzyme (ACE) converts the decapeptide angiotensin I (Ang I) into angiotensin II by releasing the C-terminal dipeptide. A novel approach combining enzymatic and electron paramagnetic resonance (EPR) studies was developed to determine the enzyme effect on Ang I containing the paramagnetic 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) at positions 1, 3, 8, and 9. Biological assays indicated that TOAC(1)-Ang I maintained partly the Ang I activity, and that only this derivative and the TOAC(3)-Ang I were cleaved by ACE. Quenching of Tyr(4) fluorescence by TOAC decreased with increasing distance between both residues, suggesting an overall partially extended structure. However, the local bend known to be imposed by the substituted diglycine TOAC is probably responsible for steric hindrance, not allowing the analogues containing TOAC at positions 8 and 9 to act as substrates. In some cases, although substrates and products differ by only two residues, the difference between their EPR spectral lineshapes allows monitoring the enzymatic reaction as a function of time.
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17
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Zerbetto M, Carlotto S, Polimeno A, Corvaja C, Franco L, Toniolo C, Formaggio F, Barone V, Cimino P. Ab Initio Modeling of CW-ESR Spectra of the Double Spin Labeled Peptide Fmoc-(Aib-Aib-TOAC)2-Aib-OMe in Acetonitrile. J Phys Chem B 2007; 111:2668-74. [PMID: 17311450 DOI: 10.1021/jp066908e] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this work we address the interpretation, via an ab initio integrated computational approach, of the CW-ESR spectra of the double spin labeled, 310-helical, peptide Fmoc-(Aib-Aib-TOAC)2-Aib-OMe dissolved in acetonitrile. Our approach is based on the determination of geometric and local magnetic parameters of the heptapeptide by quantum mechanical density functional calculations taking into account solvent and, when needed, vibrational averaging contributions. The system is then described by a stochastic Liouville equation for the two electron spins interacting with each other and with two 14N nuclear spins, in the presence of diffusive rotational dynamics. Parametrization of the diffusion rotational tensor is provided by a hydrodynamic model. CW-ESR spectra are simulated with minimal resorting to fitting procedures, proving that the combination of sensitive ESR spectroscopy and sophisticated modeling can be highly helpful in providing 3D structural and dynamic information on molecular systems.
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Affiliation(s)
- Mirco Zerbetto
- Dipartimento di Scienze Chimiche, Università degli Studi di Padova, Via Marzolo 1, I-35131 Padova, Italy
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Barone V, Polimeno A. Toward an integrated computational approach to CW-ESR spectra of free radicals. Phys Chem Chem Phys 2006; 8:4609-29. [PMID: 17047758 DOI: 10.1039/b607998a] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Interpretation of structural properties and dynamic behaviour of molecules in solution is of fundamental importance to understand their stability, chemical reactivity and catalytic action. Information can be gained, in principle, by a variety of spectroscopic techniques, magnetic as well as optical. In particular, continuous wave electron spin resonance (CW-ESR) measurements are highly informative. However, the wealth of structural and dynamic information which can be extracted from ESR spectroscopy is, at present, limited by the necessity of employing computationally efficient models, which are increasingly complex as they need to take into account diverse relaxation processes affecting the spectrum. In this paper, we address the basic theoretical tools needed to predict, essentially ab initio, CW-ESR spectra observables according to the stochastic Liouville equation (SLE) approach, combined with quantum mechanical and hybrid methods for the accurate and efficient computation of structural, spectroscopic and magnetic properties of molecular systems. We shall discuss, on one hand, the quantum mechanical calculation of magnetic observables, via density functional theory (DFT), time-dependent DFT (TD-DFT) and application of the polarizable continuum model (PCM) for the description of environmental effects, including anisotropic environments and systems where different regions are characterized by different dielectric constants. One the other hand, the explicit evaluation of dynamical effects will be discussed based on the numerically exact treatment of the SLE in the presence of several relaxation processes, which has been proven to be a challenging task.
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Affiliation(s)
- Vincenzo Barone
- Dipartimento di Chimica, Università di Napoli "Federico II", Complesso Universitario di Monte Sant'Angelo Via Cintia, I-80126, Napoli, Italy
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Affiliation(s)
- Jacopo Tomasi
- Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa, Italy.
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Ciofini I, Adamo C, Barone V. Complete structural and magnetic characterization of biological radicals in solution by an integrated quantum mechanical approach: Glycyl radical as a case study. J Chem Phys 2004; 121:6710-8. [PMID: 15473726 DOI: 10.1063/1.1791031] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
An integrated quantum mechanical approach for the structural and magnetic characterization of flexible free radicals in solution has been applied to a model of the glycyl radical engaged in peptidic chains. The hyperfine couplings computed using hybrid density functionals and purposely tailored basis sets are in good agreement with experiment when vibrational averaging effects from low frequency motions and solvent effects (both direct H bonding and bulk) are taken into the proper account. The g tensor shows a smaller dependence on the specific form of the density functional, the extension of the basis set over a standard double-zeta+polarization level, vibrational averaging, and bulk solvent effects. However, hydrogen bridges with solvent molecules belonging to the first solvation shell play a significant role. Together with their intrinsic interest, our results show that a comprehensive and reliable computational approach is becoming available for the complete characterization of open-shell systems of biological interest in their natural environment.
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Affiliation(s)
- Ilaria Ciofini
- Laboratoire d'Electrochimie et Chimie Analytique, UMR CNRS-ENSCP 7575, Ecole Nationale Supérieure de Chimie de Paris, 11 rue P. et M. Curie, F-75231 Paris Cedex 05, France
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Improta R, Barone V. Interplay of Electronic, Environmental, and Vibrational Effects in Determining the Hyperfine Coupling Constants of Organic Free Radicals. Chem Rev 2004; 104:1231-54. [PMID: 15008622 DOI: 10.1021/cr960085f] [Citation(s) in RCA: 299] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Roberto Improta
- Dipartimento di Chimica, Università Federico II, Complesso Universitario Monte S Angelo, Via Cintia, I-80126 Napoli, Italy
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