UV Photodissociation of proline-containing peptide ions: insights from molecular dynamics

Abstract : 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.
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Submitted on : Wednesday, August 26, 2015 - 3:23:52 PM
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Marion Girod, Zeljka Sanader, Marin Vojkovic, Rodolphe Antoine, Luke Macaleese, et al.. UV Photodissociation of proline-containing peptide ions: insights from molecular dynamics. Journal of The American Society for Mass Spectrometry, Springer Verlag (Germany), 2015, 26 (3), pp.432-443. ⟨10.1007/s13361-014-1038-1⟩. ⟨hal-01187318⟩



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