Dipole-Guided Electron Capture Causes Abnormal Dissociations of Phosphorylated Pentapeptides
| Autor: | Steen Brøndsted Nielsen, Christopher L. Moss, Preben Hvelplund, Jean Ann Wyer, Thomas W. Chung, František Tureček |
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| Rok vydání: | 2011 |
| Předmět: |
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Molecular Phosphopeptides Electron-capture dissociation Chemistry Electron capture Electrons Hydrogen atom Photochemistry Mass Spectrometry Ion Electron-transfer dissociation Electron transfer Fragmentation (mass spectrometry) Structural Biology Computational chemistry Physics::Atomic and Molecular Clusters Computer Simulation Ion trap Physics::Chemical Physics Oligopeptides Spectroscopy |
| Zdroj: | Moss, C L, Chung, T W, Wyer, J, Nielsen, S B, Hvelplund, P & Turecek, F 2011, ' Dipole-Guided Electron Capture Causes Abnormal Dissociations of Phosphorylated Pentapeptides ', Journal of The American Society for Mass Spectrometry, vol. 22, pp. 731-751 . https://doi.org/10.1007/s13361-011-0083-2 |
| ISSN: | 1044-0305 |
| Popis: | Electron transfer and capture mass spectra of a series of doubly charged ions that were phosphorylated pentapeptides of a tryptic type (pS,A,A,A,R) showed conspicuous differences in dissociations of charge-reduced ions. Electron transfer from both gaseous cesium atoms at 100 keV kinetic energies and fluoranthene anion radicals in an ion trap resulted in the loss of a hydrogen atom, ammonia, and backbone cleavages forming complete series of sequence z ions. Elimination of phosphoric acid was negligible. In contrast, capture of lowenergy electrons by doubly charged ions in a Penning ion trap induced loss of a hydrogen atom followed by elimination of phosphoric acid as the dominant dissociation channel. Backbone dissociations of charge-reduced ions also occurred but were accompanied by extensive fragmentation of the primary products. z-Ions that were terminated with a deaminated phosphoserine radical competitively eliminated phosphoric acid and H2PO4 radicals. A mechanism is proposed for this novel dissociation on the basis of a computational analysis of reaction pathways and transition states. Electronic structure theory calculations in combination with extensive molecular dynamics mapping of the potential energy surface provided structures for the precursor phosphopeptide dications. Electron attachment produces a multitude of low lying electronic states in charge-reduced ions that determine their reactivity in backbone dissociations and H- atom loss. The predominant loss of H atoms in ECD is explained by a distortion of the Rydberg orbital space by the strong dipolar field of the peptide dication framework. The dipolar field steers the incoming electron to preferentially attach to the positively charged arginine side chain to form guanidinium radicals and trigger their dissociations. Key words: Electron transfer dissociation, Electron capture dissociation, Phosphopeptides, Sequence ions, Dipole effects, Ion structures, Molecular dynamics calculations, Ab initio calculations |
| Databáze: | OpenAIRE |
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