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Fragmentations of protonated arginine, lysine and their methylated derivatives: concomitant losses of carbon monoxide or carbon dioxide and an amine.
- P. Shek, Junfang Zhao, Yuyong Ke, K. Siu, A. C. Hopkinson
- ChemistryThe journal of physical chemistry. A
- 13 July 2006
Results of density functional theory calculations on Protonated arginine and protonated N(alpha),N(alpha)-dimethylarginine reveal that, in such concomitant eliminations, the dissociating complex is vibrationally hot and the intermediate ion formed by losing CO or CO(2) can immediately dissociate to eliminate the amine.
The cysteine radical cation: structures and fragmentation pathways.
- Junfang Zhao, K. Siu, A. C. Hopkinson
- ChemistryPhysical chemistry chemical physics : PCCP
- 14 January 2008
A theoretical study on the structures, relative energies, isomerization reactions and fragmentation pathways of the cysteine radical cation, [NH(2)CH(CH(2)SH)COOH].+, is reported. Hybrid density…
a2 Ion Derived from Triglycine: An N1-Protonated 4-Imidazolidinone
Fragmentation of protonated peptides in the gas phase constitutes the basis for gas-phase sequencing of peptides using tandem mass spectrometry. Several mechanistic studies have indicated possible…
Two-photon-excited near-infrared emissive carbon dots as multifunctional agents for fluorescence imaging and photothermal therapy
In vitro and in vivo tests suggested that CDs can function as new multifunctional phototheranostic agents for the TPE fluorescence imaging and photothermal therapy of cancer cells.
Are the radical centers in peptide radical cations mobile? The generation, tautomerism, and dissociation of isomeric alpha-carbon-centered triglycine radical cations in the gas phase.
- I. Chu, Junfang Zhao, Minjie Xu, S. Siu, A. C. Hopkinson, K. Siu
- ChemistryJournal of the American Chemical Society
- 31 May 2008
Interconversions between these isomeric triglycine radical cations have relatively high barriers, in support of the thesis that isomerically pure [G(*)GG](+, [GG(*)G](+), and [GGG(*)](+) can be experimentally produced.
Water-Soluble Polythiophene for Two-Photon Excitation Fluorescence Imaging and Photodynamic Therapy of Cancer.
PT0 exhibited high photostabilities and pH stabilities, excellent biocompatibility, strong 1O2 generation capability, and large two-photon absorption cross sections, and it was shown that the fluorescence of PT0 was unaffected by the interference of biomolecules and metal ions.
Glutathione radical cation in the gas phase; generation, structure and fragmentation.
DFT calculations at the B3LYP/6-31++G(d,p) level of theory have been used to study interconversion between different isomers of the glutathione radical cation and to examine mechanisms by which these ions fragment.
Structure and Reactivity of the Distonic and Aromatic Radical Cations of Tryptophan
- Andrii Piatkivskyi, S. Osburn, V. Ryzhov
- ChemistryJournal of The American Society for Mass…
- 20 March 2013
AbstractIn this work, we regiospecifically generate and compare the gas-phase properties of two isomeric forms of tryptophan radical cations—a distonic indolyl N-radical (H3N+ - TrpN•) and a…
Kinetics for tautomerizations and dissociations of triglycine radical cations
Gas-phase fragmentation of protonated benzodiazepines.
Protonated 1,4-benzodiazepines dissociate in the gas phase by the common pathway of CO elimination and by unique pathways dictated by the substituents; Mechanisms of these reactions are proposed with ionic products being resonance stabilized.