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Infrared Photodissociation Spectroscopy of Electrosprayed Ions in a Fourier Transform Mass Spectrometer.
- Source :
-
Journal of the American Chemical Society . 3/23/2005, Vol. 127 Issue 11, p4076-4083. 8p. - Publication Year :
- 2005
-
Abstract
- Previous gas-phase methods for infrared photodissociation spectroscopy (IRPD) require sample volatility. Our method instead uses electrospray ionization to introduce even large nonvolatile molecules into a Fourier transform mass spectrometer, where extended (>15 s) ion storage makes possible high sensitivity spectral measurements with an OPO laser over a range of 3050-3800 cm-1. The spectra of 22 gaseous proton-bound amino acid complexes are generally correlated with the H-stretching frequencies established for O-H and N-H functional groups in solution. For theoretical structure predictions of the Gly2H+ and N-acylated Asp2H+ dimers, IRPO spectra clearly differentiate between the predicted lowest energy conformers. In contrast to solution, in the gas phase the glycine zwitterion is ∼20 kcal/mol less stable than the neutral; however, glycine is clearly zwitterionic in the gaseous GlyLysH+ dimer. The level of theory is inadequate for the larger Lys2H+ dimer, as all low energy predicted structures have free carboxyl O-H groups, in contrast to the IR spectrum. IRPD appears to be a promising new technique for providing unique information on a broad range of biomolecular and other gaseous ions, especially on noncovalent bonding involving O-H and N-H groups. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00027863
- Volume :
- 127
- Issue :
- 11
- Database :
- Academic Search Index
- Journal :
- Journal of the American Chemical Society
- Publication Type :
- Academic Journal
- Accession number :
- 16556929
- Full Text :
- https://doi.org/10.1021/ja040136n