Hydrogen atom transfer in metal ion complexes of the glutathione thiyl radical
| Autor: | Alan C. Hopkinson, John T. Lawler, Justin Kai-Chi Lau, Michael Lesslie, K. W. Michael Siu, Gardenia Pacheco, Victor Ryzhov |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Chemistry
Metal ions in aqueous solution Radical 010401 analytical chemistry Hydrogen atom 010402 general chemistry Condensed Matter Physics Photochemistry Mass spectrometry 01 natural sciences Dissociation (chemistry) 0104 chemical sciences Metal visual_art visual_art.visual_art_medium Physical and Theoretical Chemistry Quadrupole ion trap Instrumentation Isomerization Spectroscopy |
| Zdroj: | International Journal of Mass Spectrometry. 429:39-46 |
| ISSN: | 1387-3806 |
| DOI: | 10.1016/j.ijms.2017.04.012 |
| Popis: | Isomerization of the glutathione thiyl radical via hydrogen atom transfer (HAT) in its complexes with various singly and doubly charged metal ions was studied both experimentally and computationally. The glutathione thiyl radical/metal ion complexes were generated in a quadrupole ion trap mass spectrometer via collision-induced dissociation of S-nitrosoglutathione cationized by the metal ion of interest. The degree of HAT was monitored by gas-phase ion-molecule reactions of these complexes with nitric oxide – the initially formed thiyl radical species were shown previously to be reactive toward NO while the α-carbon (C α ) radicals were not. It was found that group IA metal ions facilitate HAT in the order K + > Na + > Li + > H + . This correlates well with the order of relative stability of the resulting C α species determined by density functional theory (DFT) calculations. Conversely, the glutathione thiyl radicals complexed by three different doubly-charged metal ions (Mg 2+ , Zn 2+ or Ni 2+ ) did not undergo HAT, thereby remaining the S-based radical species. This was rationalized in terms of the substantially smaller thermodynamic benefit of HAT in the case of Mg 2+ and Zn 2+ and even the endothermicity of this process for Ni 2+ , as predicted by the DFT calculations. Additionally, for the glutathione radical/Ni 2+ complex a possibility of iminol-type binding (as opposed to the “classical” keto form) to the metal ion was investigated computationally. It was found that the iminol structures are lower in energy than the keto ones, similar to the situation in the even-electron peptide/Ni 2+ complexes. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect