Selectivity in fragmentation of N-methylacetamide after resonant K-shell excitation.
Phys Chem Chem Phys
; 16(29): 15231-40, 2014 Aug 07.
Article
in En
| MEDLINE
| ID: mdl-24939520
ABSTRACT
The fragmentation pattern of the peptide model system, N-methylacetamide, is investigated using ion time-of-flight (TOF) spectroscopy after resonant K-shell excitation. Corresponding near-edge X-ray absorption fine structure (NEXAFS) spectra recorded at high resolution at the C1s, N1s and O1s edges are presented. Analysis of the ion TOF data reveals a multitude of fragmentation channels and dissociation pathways. Comparison between the excitation of six different resonances in the vicinity of the C1s, N1s and O1s edges suggests evidence for site-selective bond breaking. In particular the breaking of the peptide bond and the N-C(α) bond show a clear correlation with resonant excitation at the N1s edge. Also, stronger tendencies towards site-selective bond breaking are found for the generation of single ions compared with ion pairs. Analysis of angular distributions of ions from breakage of the peptide bond yields a fragmentation time of <400 fs.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Peptide Fragments
/
X-Ray Absorption Spectroscopy
/
Acetamides
Language:
En
Journal:
Phys Chem Chem Phys
Journal subject:
BIOFISICA
/
QUIMICA
Year:
2014
Type:
Article
Affiliation country:
Sweden