MALDI-TOF/TOF mass spectrometric assignment of Leu/lle in PVK/CAP2b neuropeptides from single neurohemal organ preparations of four flies**

MALDI-TOF/TOF tandem mass spectrometry has been applied to determine the complete sequences of the PVK/CAP2b neuropeptides in abdominal dorsal sheath tissue of the housefly Musca domestica, flesh fly Neobellieria bullata, stable fly Stomoxys calcitrans and horn fly Haematobia irritans. This peptidomic analysis of single neurohemal organ preparations allows, for the first time in arthropods, the unambiguous assignment of internal Leu/lle positions not distinguishable by previous mass spectrometric techniques. The identification of these novel neuropeptides adds to our knowledge of the peptidomes of flies, and can aid in the development of neuropeptide-based control strategies of these insect pests.