Peptidomes of Rana ridibunda species of Slovenian and Moscow populations contain the same peptide families. 19 peptides were identified in the secretion of Slovenian species by complementary (CID+HCD+ETD) methods, while 7 of them were not reported earlier. Brevinins2 appeared to be the most variable peptide family. Only 2 out of 8 brevinins 2 are the same in both (Slovenian and Moscow) populations. The main difference in the peptidome composition involves the absence of bombesin and the presence of temporin in the secretion of Slovenian frog. Another pequliqrity of this species deals with low levels of bradykinines. Application of 2D-mapping in axis NMD vs NIS demonstrated that six brevinins 2 potentially possess antimicrobial activity typical for the peptides of that family. On the contrary the novel temporin should not demonstrate any activity. Both CID and HCD modes bring to the opening of the C-terminal disulfide cycle of the intact peptides giving a chance to establish the full sequence without modification of the S-S bond. HCD spectra of non tryptic disulfide containing peptides are often difficult for interpretation due to the presence besides normal a, b/y fragment ions secondary b~*-ions as well as z-ions. However this additional information may be very helpful. For example, secondary b~*-ions in HCD spectra provide valuable structural information.
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