Gas-Phase Conformation-Specific Photofragmentation of Proline-Containing Peptide Ions

Singly-protonated proline-containing peptides with N-terminal arginine are photodissociated with vacuum ultraviolet (VUV) light in an ESI linear ion trap/orthogonal-TOF (LIT/o-TOF). When proline is the nth residue from the N-terminus, unusual bn + 2 and an + 2 ions are observed. Their formation is explained by homolytic cleavage of the Cα−C bond in conjunction with a rearrangement of electrons and an amide hydrogen. The latter is facilitated by a proline-stabilized gas-phase peptide conformation.

Graphical AbstractVacuum ultraviolet photodissociation of proline-containing peptide ions in a hybrid linear ion trap/time-of-flight mass spectrometer yields some very unusual ion fragments.Figure optionsDownload high-quality image (77 K)Download as PowerPoint slide