Studying disulfide bond rearrangement by MALDI-RTOF PSD and MALDI-TOF/RTOF high-energy CID (20 keV) experiments of peptides derived from ammodytoxins
Article first published online: 24 JAN 2011
Copyright © 2011 John Wiley & Sons, Ltd.
Journal of Mass Spectrometry
Volume 46, Issue 2, pages 153–162, February 2011
How to Cite
Brgles, M., Kurtović, T., Halassy, B., Allmaier, G. and Marchetti-Deschmann, M. (2011), Studying disulfide bond rearrangement by MALDI-RTOF PSD and MALDI-TOF/RTOF high-energy CID (20 keV) experiments of peptides derived from ammodytoxins. J. Mass Spectrom., 46: 153–162. doi: 10.1002/jms.1871
- Issue published online: 15 FEB 2011
- Article first published online: 24 JAN 2011
- Manuscript Accepted: 16 NOV 2010
- Manuscript Received: 10 SEP 2010
- post-source decay;
- high-energy CID;
- MALDI mass spectrometry;
- vicinal disulfide bonds
Ammodytoxins (Atxs) are presynaptically neurotoxic phospholipases present in Vipera ammodytes ammodytes snake venom. Atxs show a high sequence homology and contain 14 cysteines which form seven biologically relevant disulfide bridges—connecting non-neighboring cysteines. Formic acid cleavage was performed to confirm protein sequences by MALDI RTOF MS and resulted in 95.6% sequence coverage exhibiting only few formylations. Cysteine-containing peptides showed adjacent signals 2 and/or 4 Da lower (according to the number of cysteines present in the peptide) than the theoretical molecular weight indicating disulfide bridge rearrangement. Post-source decay (PSD) and high-energy collision-induced dissociation (CID) at 20 keV experiments showed fragmentation pattern unique for the reduced, thiol group containing and the oxidized, disulfide bridge harboring peptides. Besides typical low-energy fragment ions observed during PSD experiments (a-, b-, y-type ions), additional high-energy fragment ions (c-, x-, w-, d-type and internal fragments) of significant intensity were generated during fragmentation at 20 keV. In the case of charge directing N- and C-termini, x- and w-type ions were also observed during PSD. Good and up to complete sequence coverage was achieved for all studied peptides from Atxs in the case of high-energy CID, whereas PSD lacked information particularly for larger peptides. Copyright © 2011 John Wiley & Sons, Ltd.