Capillary cation exchange column

Since 2002, on-line nanoscale LC-ESI-MS/MS was used for the analysis of the peptidome of. Drosophila samples. This combination greatly improves the sensitivity of detection. Starting from only 50 larval Drosophila CNS, 28 peptides were isolated and sequenced in an on-line quadrupole time-of-flight mass spectrometer [27]. Later, two-dimensional capillary LC-ESI-MS/MS has enhanced the coverage of this peptidomics analysis with the identification of twenty additional peptides [31]. The CNS extract has been first fractionated onto a strong cation-exchange column then onto a reversed-phase column before ESI-MS/MS analysis. Recently this approach has been applied to Drosophila larvae hemolymph to identify new peptides induced by a septic injury [22]. Most of the identified molecules correspond to truncated forms or propeptides of known AMPs and DIMs [15,20,21], but two previously unknown peptide precursors, potentially involved in the innate immune response, have been also detected by this way. 

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