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Mechanism and Kinetics of Copper Complexes Binding to the Influenza A M2 S31N and S31N/G34E Channels. Biophys J 2020; 120:168-177. [PMID: 33248127 DOI: 10.1016/j.bpj.2020.11.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/21/2020] [Accepted: 11/13/2020] [Indexed: 01/13/2023] Open
Abstract
Copper(II) is known to bind in the influenza virus His37 cluster in the homotetrameric M2 proton channel and block the proton current needed for uncoating. Copper complexes based on iminodiacetate also block the M2 proton channel and show reduced cytotoxicity and zebrafish-embryo toxicity. In voltage-clamp oocyte studies using the ubiquitous amantadine-insensitive M2 S31N variant, the current block showed fast and slow phases, in contrast to the single phase found for amantadine block of wild-type M2. Here, we evaluate the mechanism of block by copper adamantyl iminodiacitate and copper cyclooctyl iminodiacitate complexes and address whether the complexes can coordinate with one or more of the His37 imidazoles. The current traces were fitted to parametrized master equations. The energetics of binding and the rate constants suggest that the first step is copper complex binding within the channel, and the slow step in the current block is the formation of a Cu-histidine coordination complex. Solution-phase isothermal titration calorimetry and density functional theory (DFT) calculations indicate that imidazole binds to the copper complexes. Structural optimization using DFT reveals that the complexes fit inside the channel and project the Cu(II) toward the His37 cluster, allowing one imidazole to form a coordination complex with Cu(II). Electrophysiology and DFT studies also show that the complexes block the G34E amantadine-resistant mutant despite some crowding in the binding site by the glutamates.
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2
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Akinyemi TE, Wu RR, Nei YW, Cunningham NA, Roy HA, Steill JD, Berden G, Oomens J, Rodgers MT. Influence of Transition Metal Cationization versus Sodium Cationization and Protonation on the Gas-Phase Tautomeric Conformations and Stability of Uracil: Application to [Ura+Cu] + and [Ura+Ag]<sup/>. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:2438-2453. [PMID: 28895083 DOI: 10.1007/s13361-017-1771-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 07/22/2017] [Accepted: 07/22/2017] [Indexed: 05/17/2023]
Abstract
The gas-phase conformations of transition metal cation-uracil complexes, [Ura+Cu]+ and [Ura+Ag]+, were examined via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra were measured over the IR fingerprint and hydrogen-stretching regions. Structures and linear IR spectra of the stable tautomeric conformations of these complexes were initially determined at the B3LYP/6-31G(d) level. The four most stable structures computed were also examined at the B3LYP/def2-TZVPPD level to improve the accuracy of the predicted IR spectra. Two very favorable modes of binding are found for [Ura+Cu]+ and [Ura+Ag]+ that involve O2N3 bidentate binding to the 2-keto-4-hydroxy minor tautomer and O4 monodentate binding to the canonical 2,4-diketo tautomer of Ura. Comparisons between the measured IRMPD and calculated IR spectra enable elucidation of the conformers present in the experiments. These comparisons indicate that both favorable binding modes are represented in the experimental tautomeric conformations of [Ura+Cu]+ and [Ura+Ag]+. B3LYP suggests that Cu+ exhibits a slight preference for O4 binding, whereas Ag+ exhibits a slight preference for O2N3 binding. In contrast, MP2 suggests that both Cu+ and Ag+ exhibit a more significant preference for O2N3 binding. The relative band intensities suggest that O4 binding conformers comprise a larger portion of the population for [Ura+Ag]+ than [Ura+Cu]+. The dissociation behavior and relative stabilities of the [Ura+M]+ complexes, M+ = Cu+, Ag+, H+, and Na+) are examined via energy-resolved collision-induced dissociation experiments. The IRMPD spectra, dissociation behaviors, and binding preferences of Cu+ and Ag+ are compared with previous and present results for those of H+ and Na+. Graphical Abstract ᅟ.
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Affiliation(s)
- T E Akinyemi
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - R R Wu
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - Y-W Nei
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - N A Cunningham
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - H A Roy
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - J D Steill
- Institute for Molecules and Materials, FELIX Facility, Radboud University Nijmegen, Toernooiveld 7, 6525 ED, Nijmegen, The Netherlands
| | - G Berden
- Institute for Molecules and Materials, FELIX Facility, Radboud University Nijmegen, Toernooiveld 7, 6525 ED, Nijmegen, The Netherlands
| | - J Oomens
- Institute for Molecules and Materials, FELIX Facility, Radboud University Nijmegen, Toernooiveld 7, 6525 ED, Nijmegen, The Netherlands
- van't Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - M T Rodgers
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA.
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Gao J, Bouwman J, Berden G, Oomens J. The Influence of Metal Ion Binding on the IR Spectra of Nitrogen-Containing PAHs. J Phys Chem A 2016; 120:7800-7809. [DOI: 10.1021/acs.jpca.6b05060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Juehan Gao
- Radboud
University, FELIX Laboratory, Institute for Molecules and Materials, Toernooiveld 7c, 6525ED Nijmegen, The Netherlands
| | - Jordy Bouwman
- Radboud
University, FELIX Laboratory, Institute for Molecules and Materials, Toernooiveld 7c, 6525ED Nijmegen, The Netherlands
| | - Giel Berden
- Radboud
University, FELIX Laboratory, Institute for Molecules and Materials, Toernooiveld 7c, 6525ED Nijmegen, The Netherlands
| | - Jos Oomens
- Radboud
University, FELIX Laboratory, Institute for Molecules and Materials, Toernooiveld 7c, 6525ED Nijmegen, The Netherlands
- Van’t
Hoff Institute for Molecular Sciences, University of Amsterdam, Science
Park 904, 1098XH Amsterdam, The Netherlands
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Rodgers MT, Armentrout PB. Cationic Noncovalent Interactions: Energetics and Periodic Trends. Chem Rev 2016; 116:5642-87. [PMID: 26953819 DOI: 10.1021/acs.chemrev.5b00688] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
In this review, noncovalent interactions of ions with neutral molecules are discussed. After defining the scope of the article, which excludes anionic and most protonated systems, methods associated with measuring thermodynamic information for such systems are briefly recounted. An extensive set of tables detailing available thermodynamic information for the noncovalent interactions of metal cations with a host of ligands is provided. Ligands include small molecules (H2, NH3, CO, CS, H2O, CH3CN, and others), organic ligands (O- and N-donors, crown ethers and related molecules, MALDI matrix molecules), π-ligands (alkenes, alkynes, benzene, and substituted benzenes), miscellaneous inorganic ligands, and biological systems (amino acids, peptides, sugars, nucleobases, nucleosides, and nucleotides). Hydration of metalated biological systems is also included along with selected proton-based systems: 18-crown-6 polyether with protonated peptides and base-pairing energies of nucleobases. In all cases, the literature thermochemistry is evaluated and, in many cases, reanchored or adjusted to 0 K bond dissociation energies. Trends in these values are discussed and related to a variety of simple molecular concepts.
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Affiliation(s)
- M T Rodgers
- Department of Chemistry, Wayne State University , Detroit, Michigan 48202, United States
| | - P B Armentrout
- Department of Chemistry, University of Utah , Salt Lake City, Utah 84112, United States
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Gao J, Berden G, Rodgers MT, Oomens J. Interaction of Cu(+) with cytosine and formation of i-motif-like C-M(+)-C complexes: alkali versus coinage metals. Phys Chem Chem Phys 2016; 18:7269-77. [PMID: 26894838 DOI: 10.1039/c6cp00234j] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The Watson-Crick structure of DNA is among the most well-known molecular structures of our time. However, alternative base-pairing motifs are also known to occur, often depending on base sequence, pH, or the presence of cations. Pairing of cytosine (C) bases induced by the sharing of a single proton (C-H(+)-C) may give rise to the so-called i-motif, which occurs primarily in expanded trinucleotide repeats and the telomeric region of DNA, particularly at low pH. At physiological pH, silver cations were recently found to stabilize C dimers in a C-Ag(+)-C structure analogous to the hemiprotonated C-dimer. Here we use infrared ion spectroscopy in combination with density functional theory calculations at the B3LYP/6-311G+(2df,2p) level to show that copper in the 1+ oxidation state induces an analogous formation of C-Cu(+)-C structures. In contrast to protons and these transition metal ions, alkali metal ions induce a different dimer structure, where each ligand coordinates the alkali metal ion in a bidentate fashion in which the N3 and O2 atoms of both cytosine ligands coordinate to the metal ion, sacrificing hydrogen-bonding interactions between the ligands for improved chelation of the metal cation.
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Affiliation(s)
- Juehan Gao
- Radboud University, Institute for Molecules and Materials, FELIX Laboratory, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands.
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Boussouf K, Khairat T, Prakash M, Komiha N, Chambaud G, Hochlaf M. Structure, Spectroscopy, and Bonding within the Zn(q+)-Imidazole(n) (q = 0, 1, 2; n = 1-4) Clusters and Implications for Zeolitic Imidazolate Frameworks and Zn-Enzymes. J Phys Chem A 2015; 119:11928-40. [PMID: 26565743 DOI: 10.1021/acs.jpca.5b09500] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Using density functional theory (DFT) with dispersion correction and ab initio post Hartree-Fock methods, we treat the bonding, the structure, the stability, and the spectroscopy of the complexes between Zn(q+) and imidazole (Im), Zn(q+)Imn (where q = 0, 1 and 2; n = 1-4). These entities are subunits of zeolitic imidazolate frameworks (ZIFs) and Zn-enzymes, which possess relevant roles in industrial and biological domains, respectively. We also investigate the Imn (n = 2-4) clusters for comparison. For each species, we determine several new structures that were not found previously. Our calculations show a competition between atomic metal solvation, by either σ-type interactions or π-stacking type interaction, and proton transfer through hydrogen bonding (H-bonding) in charged species. This results in several geometrical environments around the metal. These are connected with structural properties and the functional role of Zn cation within ZIFs and Zn-enzymes. Moreover, we show that the Zn(2+)Imn subunits do not absorb in the visible domain, which may be related to the photostability of ZIFs. Our findings are important for the development of new applications of ZIFs and metalloenzymes.
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Affiliation(s)
- K Boussouf
- LS3ME-Equipe de Chimie Théorique et Modélisation, Faculté des Sciences Rabat, Université Mohamed V , Rabat, Morocco.,Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, Université Paris-Est , 5 bd Descartes, 77454 Marne-la-Vallée, France
| | - T Khairat
- LS3ME-Equipe de Chimie Théorique et Modélisation, Faculté des Sciences Rabat, Université Mohamed V , Rabat, Morocco
| | - M Prakash
- Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, Université Paris-Est , 5 bd Descartes, 77454 Marne-la-Vallée, France
| | - N Komiha
- LS3ME-Equipe de Chimie Théorique et Modélisation, Faculté des Sciences Rabat, Université Mohamed V , Rabat, Morocco
| | - G Chambaud
- Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, Université Paris-Est , 5 bd Descartes, 77454 Marne-la-Vallée, France
| | - M Hochlaf
- Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, Université Paris-Est , 5 bd Descartes, 77454 Marne-la-Vallée, France
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7
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Vikse KL, Chen P. Elementary Reactions at Organocopper(III): A Gas-Phase and Theoretical Study. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00038] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Krista L. Vikse
- Laboratorium
für Organische
Chemie, ETH Zürich, Zürich 8093, Switzerland
| | - Peter Chen
- Laboratorium
für Organische
Chemie, ETH Zürich, Zürich 8093, Switzerland
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Noh DH, Lee SJC, Lee JW, Kim HI. Host-guest chemistry in the gas phase: complex formation of cucurbit[6]uril with proton-bound water dimer. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:410-421. [PMID: 24435795 DOI: 10.1007/s13361-013-0795-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Revised: 11/26/2013] [Accepted: 11/26/2013] [Indexed: 06/03/2023]
Abstract
The hydration of cucurbit[6]uril (CB[6]) in the gas phase is investigated using electrospray ionization traveling wave ion mobility mass spectrometry (ESI-TWIM-MS). Highly abundant dihydrated and tetrahydrated species of diprotonated CB[6] are found in the ESI-TWIM-MS spectrum. The hydration patterns of the CB[6] ion and the dissociation patterns of the hydrated CB[6] ion indicate that two water molecules are bound to each other, forming a water dimer in the CB[6] complex. Ion mobility studies combined with the structures calculated by density functional theory suggest that the proton-bound water dimer is present as a Zundel-like structure in the CB[6] portal, forming a hydrogen bond network with carbonyl groups of the CB[6]. When a large guest molecule is bound to a CB[6] portal, water molecules cannot bind to the portal. In addition, the strong binding energy of the water dimer blocks the portal, hindering the insertion of the long alkyl chain of the guest molecule into the CB[6] cavity. With small alkali metal cations, such as Li(+) and Na(+), a single water molecule interacts with the CB[6] portal, forming hydrogen bonds with the carbonyl groups of CB[6]. A highly stable Zundel-like structure of the proton-bound water dimer or a metal-bound water molecule at the CB[6] portal is suggested as an initial hydration process for CB[6], which is only dissolved in aqueous solution with acid or alkali metal ions.
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Affiliation(s)
- Dong Hun Noh
- Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, Republic of Korea
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9
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Chen Y, Chinthaka SDM, Rodgers MT. Silver cation affinities of monomeric building blocks of polyethers and polyphenols determined by guided ion beam tandem mass spectrometry. J Phys Chem A 2013; 117:8274-84. [PMID: 23914909 DOI: 10.1021/jp402224t] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Energy-resolved collision-induced dissociation (CID) of seven silver cation-ligand complexes, Ag(+)(L), with Xe is studied using guided ion beam tandem mass spectrometry techniques. The ligands, L, investigated are monomeric building blocks of polyethers and polyphenols including phenol, 2-hydroxyphenol, 3-hydroxyphenol, 4-hydroxyphenol, 2-hydroxymethyl phenol, 3-hydroxymethyl phenol, and 4-hydroxymethyl phenol. In all cases, Ag(+) is observed as the primary CID product, corresponding to endothermic loss of the intact neutral ligand. The kinetic-energy-dependent cross sections for CID of these Ag(+)(L) complexes are analyzed using an empirical threshold law to extract absolute 0 and 298 K Ag(+)-L bond dissociation energies (BDEs). Density functional theory calculations at the B3LYP/6-31G* level of theory are used to determine the structures of the neutral ligands and their complexes to Ag(+) using either the Stuttgart RSC 1997 valence basis set and effective core potential (SRSC ECP) or DZVP-DFT to describe Ag(+). Theoretical BDEs are determined at the B3LYP/6-311+G(2d,2p) level of theory again using the SRSC ECP or DZVP-DFT for Ag(+). For all systems, the most stable binding conformations found involve cation-π interactions when the SRSC ECP is used to describe Ag(+). When DZVP-DFT is employed, the most stable binding geometries remain cation-π complexes except for the complex to 2HP, where the ground-state conformer involves bidentate binding of Ag(+) to the hydroxyl oxygen atoms of both substituents. The agreement between the measured and calculated BDEs is excellent with a MAD of 2.9 ± 1.7 kJ/mol when the SRSC ECP is used to describe Ag(+) and less satisfactory for DZVP-DFT, which underestimates the strength of binding in these systems by ~14% or 26.0 ± 6.7 kJ/mol.
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Affiliation(s)
- Y Chen
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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10
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Chen Y, Rodgers MT. Structural and Energetic Effects in the Molecular Recognition of Amino Acids by 18-Crown-6. J Am Chem Soc 2012; 134:5863-75. [DOI: 10.1021/ja211021h] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Yu Chen
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - M. T. Rodgers
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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11
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Dong J, Vachet RW. Coordination sphere tuning of the electron transfer dissociation behavior of Cu(II)-peptide complexes. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:321-9. [PMID: 22161629 PMCID: PMC3265685 DOI: 10.1007/s13361-011-0299-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 11/04/2011] [Accepted: 11/15/2011] [Indexed: 05/21/2023]
Abstract
In contrast to previous electron capture dissociation (ECD) studies, we find that electron transfer dissociation (ETD) of Cu(II)-peptide complexes can generate c- and z-type product ions when the peptide has a sufficient number of strongly coordinating residues. Double-resonance experiments, ion-molecule reactions, and collision-induced dissociation (CID) prove that the c and z product ions are formed via typical radical pathways without the associated reduction of Cu(II), despite the high second ionization energy of Cu. A positive correlation between the number of Cu(II) binding groups in the peptide sequence and the extent of c and z ion formation was also observed. This trend is rationalized by considering that the recombination energy of Cu(II) can be lowered by strong binding ligands to an extent that enables electron transfer to non-Cu sites (e.g., protonation sites) to compete with Cu(II) reduction, thereby generating c/z ions in a manner similar to that observed for protonated (i.e., nonmetalated) peptides.
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Affiliation(s)
| | - Richard W. Vachet
- Corresponding author address: Department of Chemistry, LGRT 701, 710 N. Pleasant St., University of Massachusetts, Amherst, MA 01003, Fax: 413-545-4490,
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Chen Y, Rodgers MT. Structural and Energetic Effects in the Molecular Recognition of Protonated Peptidomimetic Bases by 18-Crown-6. J Am Chem Soc 2012; 134:2313-24. [DOI: 10.1021/ja2102345] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yu Chen
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - M. T. Rodgers
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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13
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Zhang S, Xu L, Dong J, Cheng P, Zhou Z, Fu J. Collision-induced dissociation of singly and doubly charged CuII–cytidine complexes in the gas phase: an experimental and computational study. RSC Adv 2012. [DOI: 10.1039/c2ra01293f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
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ABIRAM A, KOLANDAIVEL P. INTERACTION OF THE TAUTOMERIC STATES OF HISTIDINE WITH Cu AND Zn METAL IONS – A THEORETICAL STUDY. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2011. [DOI: 10.1142/s021963360900499x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A density functional study on the interaction of Cu 2+ and Zn 2+ metal ions at the predominant positions of N τ– H and N π– H histidine tautomers has been performed. The fully optimized energy of the isolated histidine tautomers at B3LYP/6-311++G** level of theory depicts N τ– H tautomer to be much stable compared to that of the N π– H tautomer. The interaction of metal ions forms bidentate and tridentate complexes with N τ– H tautomer, while it is absent in the case of N π– H tautomer emphasizing the role of former in structural determination of liganated proteins. The Zn 2+ ion induces a barrier-free proton transfer when interacted at the carbonyl position of N τ– H histidine tautomer necessitating the tautomer to be in the zwitterionic form for complexation. The thermodynamical analysis predicts a blue shift in the NH and CO stretching vibrational frequencies and suggests N τ– H tautomer to be best suitable for Cu 2+ and Zn 2+ ion interactions. The topological and charge transfer studies in concert with frontier molecular orbital (FMO) analysis confirm the covalent interaction, validating the findings based on the geometrical data.
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Affiliation(s)
- A. ABIRAM
- Department of Physics, Bharathiar University, Coimbatore-641 046, India
| | - P. KOLANDAIVEL
- Department of Physics, Bharathiar University, Coimbatore-641 046, India
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15
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Rannulu NS, Rodgers MT. Noncovalent Interactions of Ni+ with N-Donor Ligands (Pyridine, 4,4′-Dipyridyl, 2,2′-Dipyridyl, and 1,10-Phenanthroline): Collision-Induced Dissociation and Theoretical Studies. J Phys Chem A 2009; 113:4534-48. [DOI: 10.1021/jp8112045] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- N. S. Rannulu
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202
| | - M. T. Rodgers
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202
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16
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Yang Z, Rannulu NS, Chu Y, Rodgers MT. Bond Dissociation Energies and Equilibrium Structures of Cu+(MeOH)x, x = 1−6, in the Gas Phase: Competition between Solvation of the Metal Ion and Hydrogen-Bonding Interactions. J Phys Chem A 2008; 112:388-401. [DOI: 10.1021/jp076964v] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Z. Yang
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202
| | - N. S. Rannulu
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202
| | - Y. Chu
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202
| | - M. T. Rodgers
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202
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Cheng P, Bohme DK. Gas-Phase Formation of Radical Cations of Monomers and Dimers of Guanosine by Collision-Induced Dissociation of Cu(II)−Guanosine Complexes. J Phys Chem B 2007; 111:11075-82. [PMID: 17715957 DOI: 10.1021/jp071933l] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An electrosprayed water/methanol solution of guanosine and Cu(NO3)2 was observed to give rise to gas-phase copper complexed ions of [CuLn]*2+, [CuL(MeOH)n]*2+, and [CuG n(NO3)]*+, as well as the ions [L]*+, [L+H]+, [G]*+, and [G+H]+ (L=guanosine, G=guanine). The Collision-Induced Dissociation (CID) of [CuL3]*2+ and [CuL(MeOH)n]*2+ (n=2, 3) generates guanosine radical cations [L]*+, while dimeric guanosine radical cations [L2]*+ are generated in the dissociation of [CuL4]*2+. Protonated guanosine [L+H]+ is one of the main products in the primary dissociation of [CuL2]*2+, while the dissociation of the higher-order [CuG2]*2+ produces the [G]*+ radical cation. The guanosine dimer radical cation, [L2]*+ presumably arises from the interaction of two guanosine molecules via proton and hydrogen bonding and is observed to dissociate into [L+H]+ and [L-H]* at low energies. We propose that the first two ligands bind strongly with Cu(II) through N7 and O6 to form a [CuL2]*2+ complex with a four-coordinated planar structure and that a third ligand binds loosely with copper to form [CuL3]*2+. Additional ligation observed in the formation of [CuLn]*2+ (n<or=6) ions is presumed to occur by hydrogen bonding. The ribose group of guanosine appears to play an important role in the stabilization of the doubly charged Cu-guanosine complex and in intraligand proton transfer upon CID. The molecular radical cations [L]*+ observed in the ESI-MS spectrum at low declustering potentials originate primarily from [CuL(MeOH)2,3]*2+ complexes which can dissociate more easily than [CuL3]*2+.
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Affiliation(s)
- Ping Cheng
- Department of Chemistry, Centre for Research in Mass Spectrometry and Centre for Research in Earth and Space Science, York University, Toronto, Ontario, Canada, M3J 1P3
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18
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Rannulu NS, Rodgers MT. Noncovalent Interactions of Cu+withN-Donor Ligands (Pyridine, 4,4-Dipyridyl, 2,2-Dipyridyl, and 1,10-Phenanthroline): Collision-Induced Dissociation and Theoretical Studies. J Phys Chem A 2007; 111:3465-79. [PMID: 17439193 DOI: 10.1021/jp066903h] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Collision-induced dissociation of complexes of Cu+ bound to a variety of N-donor ligands (N-L) with Xe is studied using guided ion beam tandem mass spectrometry. The N-L ligands examined include pyridine, 4,4-dipyridyl, 2,2-dipyridyl, and 1,10-phenanthroline. In all cases, the primary and lowest-energy dissociation channel observed corresponds to the endothermic loss of a single intact N-L ligand. Sequential dissociation of additional N-L ligands is observed at elevated energies for the pyridine and 4,4-dipyridyl complexes containing more than one ligand. Ligand exchange processes to produce Cu+Xe are also observed as minor reaction pathways in several systems. The primary cross section thresholds are interpreted to yield 0 and 298 K bond dissociation energies (BDEs) after accounting for the effects of multiple ion-neutral collisions, the kinetic and internal energy distributions of the reactants, and dissociation lifetimes. Density functional theory calculations at the B3LYP/6-31G* level are performed to obtain model structures, vibrational frequencies, and rotational constants for the neutral N-L ligands and the Cu+(N-L)x complexes. The relative stabilities of the various conformations of these N-L ligands and Cu+(N-L)x complexes as well as theoretical BDEs are determined from single point energy calculations at the B3LYP/6-311+G(2d,2p) level of theory using B3LYP/6-31G* optimized geometries. Excellent agreement between theory and experiment is observed for all complexes containing one or two N-L ligands, while theory systematically underestimates the strength of binding for complexes containing more than two N-L ligands. The ground-state structures of these complexes and the trends in the sequential BDEs are explained in terms of stabilization gained from sd-hybridization and repulsive ligand-ligand interactions. The nature of the binding interactions in the Cu+(N-L)x complexes are examined via natural bond orbital analyses.
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Affiliation(s)
- N S Rannulu
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
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Wang X, Lee JS, Yang DS. Electron Spectroscopy, Molecular Structures, and Binding Energies of Al- and Cu-Imidazole. J Phys Chem A 2006; 110:12777-84. [PMID: 17125291 DOI: 10.1021/jp0649605] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Al- and Cu-imidazole are produced in laser-vaporization supersonic molecular beams and studied with pulsed field ionization-zero electron kinetic energy (ZEKE) spectroscopy and second-order Møller-Plesset (MP2) theory. The sigma and pi structures of these complexes are predicted by MP2 calculations, but only the sigma structures are identified by the experimental measurements. For these sigma structures, adiabatic ionization energies and several vibrational frequencies are measured from the ZEKE spectra, the ground electronic states of the neutral and ionized complexes are determined by comparing the observed and calculated spectra, and the metal-ligand bond dissociation energies of the neutral states are derived by using a thermochemical relation. The measured vibrational modes include the metal-ligand stretch and bend and ligand ring distortions. The metal-ligand stretch frequencies of these transient complexes are compared with those of coordinately saturated, stable metal compounds, and the ligand-based distortion frequencies are compared with those of the free ligand. Al-imidazole has a larger bond dissociation energy than Cu-imidazole, although the opposite order was previously found for the corresponding ions. The weaker bonding of the Cu complex is attributed to the antibonding interaction and the electron repulsion between the Cu 4s and N lone-pair electrons.
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Affiliation(s)
- Xu Wang
- Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055, USA
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Raffa DF, Rickard GA, Rauk A. Ab initio modelling of the structure and redox behaviour of copper(I) bound to a His–His model peptide: relevance to the β-amyloid peptide of Alzheimer’s disease. J Biol Inorg Chem 2006; 12:147-64. [PMID: 17013614 DOI: 10.1007/s00775-006-0175-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 09/06/2006] [Indexed: 10/24/2022]
Abstract
A contributing factor to the pathology of Alzheimer's disease is the generation of reactive oxygen species, most probably a consequence of the beta-amyloid (Abeta) peptide coordinating copper ions. Experimental and theoretical results indicate that His13 and His14 are the two most firmly established ligands in the coordination sphere of Cu(II) bound to Abeta. Abeta1-42 is known to reduce Cu(II) to Cu(I). The Abeta-Cu(II) complex has been shown to catalytically generate H(2)O(2) from reducing agents and O(2). Cu(II) in the presence of Abeta has been reported to have a formal reduction potential of +0.72-0.77 V (vs. the standard hydrogen electrode). Quantum chemical calculations using the B3LYP hybrid density functional method with the 6-31G(d) basis set were performed to model the reduction of previously studied Cu(II) complexes representing the His13-His14 portion of Abeta (Raffa et al. in J. Biol. Inorg. Chem. 10:887-902, 2005). The effects of solvation were accommodated using the CPCM method. The most stable complex between Cu(I) and the model compound, 3-(5-imidazolyl)propionylhistamine (1) involves tricoordinated Cu(I) in a distorted-T geometry, with the Npi of both imidazoles as well as the oxygen of the backbone carbonyl bound to copper. This model would be the most likely representation of a Cu(I) binding site for a His-His peptide in aqueous solution. A variety of possible redox processes are discussed.
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Affiliation(s)
- Duilio F Raffa
- Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
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Ke Y, Verkerk UH, Shek PYI, Hopkinson AC, Siu KWM. Stable Gas-Phase Radical Cations of Dimeric Tryptophan and Tyrosine Derivatives. J Phys Chem B 2006; 110:8517-23. [PMID: 16623540 DOI: 10.1021/jp060029a] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Stable radical cations of dimeric amino acid derivatives of tryptophan and tyrosine were generated by collision-induced dissociation of [Cu(II)(diethylenetriamine)(amino acid derivative)2]*2+. The yields of the dimer radical cations were dependent on both the auxiliary ligand and the tryptophan or tyrosine derivatives used. Amino acid derivatives with an unmodified carboxylic acid group did not generate dimer radical cations. For the amino acid derivatives Ac-Trp-OMe and Ac-Trp-NH2 (Ac is N-acetyl; OMe and NH2 are the methyl ester and amide modifications of the C-terminal carboxylic group), no auxiliary ligand was required for generating the dimer radical cations. Collision-induced dissociation of the [Cu(II)(amino acid derivative)4]*2+ precursor generated the dimer radical cation [(amino acid derivative)2]*+. Stabilizing interactions, most likely involving hydrogen bonding, between the two amino acid derivatives are proposed to account for observation of the dimer radical cations. Dissociation of these ions yields protonated or radical cationic amino acid derivatives; these observations are consistent with the expectation of proton competition between monomeric units, whose proton affinities were calculated using density functional theory.
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Affiliation(s)
- Yuyong Ke
- Department of Chemistry and Centre for Research in Mass Spectrometry, York University, 4700 Keele Street, Toronto, Ontario M3J 1P3, Canada
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