UV Photodissociation of Proline-containing Peptide Ions: Insights from Molecular Dynamics

作者：Girod Marion^*; Sanader Zeljka; Vojkovic Marin; Antoine Rodolphe; MacAleese Luke; Lemoine Jerome; Bonacic Koutecky Vlasta; Dugourd Philippe

来源：Journal of the American Society for Mass Spectrometry, 2015, 26(3): 432-443.

DOI：10.1007/s13361-014-1038-1

• Photodissociation
• Proline-containing peptides
• Fragmentation
• Molecular dynamics
• H/D exchange

UV photodissociation of proline-containing peptide ions leads to unusual product ions. In this paper, we report laser-induced dissociation of a series of proline-containing peptides at 213 nm. We observe specific fragmentation pathways corresponding to the formation of (y-2), (a + 2) and (b + 2) fragment ions. This was not observed at 266 nm or for peptides which do not contain proline residues. In order to obtain insights into the fragmentation dynamics at 213 nm, a small peptide (RPK for arginine-proline-lysine) was studied both theoretically and experimentally. Calculations of absorption spectra and non-adiabatic molecular dynamics (MD) were made. Second and third excited singlet states, S-2 and S-3, lie close to 213 nm. Non-adiabatic MD simulation starting from S-2 and S-3 shows that these transitions are followed by C-C and C-N bond activation close to the proline residue. After this first relaxation step, consecutive rearrangements and proton transfers are required to produce unusual (y-2), (a + 2) and (b + 2) fragment ions. These fragmentation mechanisms were confirmed by H/D exchange experiments.

• 出版日期2015-3