Naslov
Studying Disulfide Bond Rearrangement by MALDI-RTOF PSD and MALDI-TOF/RTOF High-Energy CID (20 keV) Experiments of Peptides Derived from Ammodytoxins

Autori
Brgles, Marija ; Kurtović, Tihana ; Halassy, Beata ; Allmaier, Günter ; Marchetti-Deschmann, Martina

Izvornik
Journal of mass spectrometry (1076-5174) 46 (2011), 2; 153-162

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
ammodytoxin; post-source decay; high-energy CID; MALDI mass spectrometry; vicinal disulfide bonds

Sažetak
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 7 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. Beside 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 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.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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