Rearrangement Pathways of the a4 Ion of Protonated YGGFL Characterized by IR Spectroscopy and Modeling
| Autor: | Béla Paizs, Philippe Maître, Benjamin J. Bythell |
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| Rok vydání: | 2012 |
| Předmět: |
Ions
Models Molecular Spectrometry Mass Electrospray Ionization education.field_of_study Spectrophotometry Infrared Chemistry 010401 analytical chemistry Population Infrared spectroscopy Protonation 010402 general chemistry Mass spectrometry 01 natural sciences 0104 chemical sciences Ion Crystallography Structural Biology Computational chemistry Potential energy surface Density functional theory Quadrupole ion trap education Oligopeptides Spectroscopy |
| Zdroj: | Journal of the American Society for Mass Spectrometry. 23:664-675 |
| ISSN: | 1044-0305 |
| Popis: | The structure of the a (4) ion from protonated YGGFL was studied in a quadrupole ion trap mass spectrometer by 'action' infrared spectroscopy in the 1000-2000 cm(-1) ('fingerprint') range using the CLIO Free Electron Laser. The potential energy surface (PES) of this ion was characterized by detailed molecular dynamics scans and density functional theory calculations exploring a large number of isomers and protonation sites. IR and theory indicate the a (4) ion population is primarily populated by the rearranged, linear structure proposed recently (Bythell et al., J. Am. Chem. Soc. 2010, 132, 14766). This structure contains an imine group at the N- terminus and an amide group -CO-NH(2) at the C-terminus. Our data also indicate that the originally proposed N-terminally protonated linear structure and macrocyclic structures (Polfer et al., J. Am. Chem. Soc. 2007, 129, 5887) are also present as minor populations. The clear differences between the present and previous IR spectra are discussed in detail. This mixture of gas-phase structures is also in agreement with the ion mobility spectrum published by Clemmer and co-workers recently (J. Phys. Chem. A 2008, 112, 1286). Additionally, the calculated cross-sections for the rearranged structures indicate these correspond to the most abundant (and previously unassigned) feature in Clemmer's work. |
| Databáze: | OpenAIRE |
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