Fragmentation reactions of deprotonated peptides containing proline. The proline effect
Article first published online: 22 JUL 2005
Copyright © 2005 John Wiley & Sons, Ltd.
Journal of Mass Spectrometry
Volume 40, Issue 9, pages 1173–1186, September 2005
How to Cite
Harrison, A. G. and Young, A. B. (2005), Fragmentation reactions of deprotonated peptides containing proline. The proline effect. J. Mass Spectrom., 40: 1173–1186. doi: 10.1002/jms.891
- Issue published online: 30 AUG 2005
- Article first published online: 22 JUL 2005
- Manuscript Accepted: 10 MAY 2005
- Manuscript Received: 3 JAN 2005
- Natural Sciences and Engineering Research Council (Canada).
- proline effect;
- peptide fragmentation;
- negative ions;
The collision-induced dissociation (CID) fragmentation reactions of a variety of deprotonated peptides containing proline have been studied in detail using MS2 and MS3 experiments, deuterium labelling and accurate mass measurements when necessary. The [MHCO2]− (a2) ion derived from H-Pro-Xxx-OH dipeptides shows an unusual fragmentation involving loss of C2H4; this fragmentation reaction is not observed for larger peptides. The primary fragmentation reactions of deprotonated tripeptides with an N-terminal proline are formation of a3 and y1 ions. When proline is in the central position of tripeptides, a3, y2 and y1 ions are the primary fragmentation products of [MH]−, while when the proline is in the C-terminal position, a3and y1 ions are the major primary products. In the latter case, the a3 ion fragments primarily to the ″b2 ion; further evidence is presented that the ″b2 ions have a deprotonated oxazolone structure. Larger deprotonated peptides having at least two amino acid residues N-terminal to proline show a distinct preference for cleavage of the amide bond N-terminal to proline to form, mainly, the appropriate y ion. This proline effect is compared and contrasted with the similar proline effect observed in the fragmentation of protonated peptides containing proline. Copyright © 2005 John Wiley & Sons, Ltd.