The crustacean sinus gland (SG) is a well-defined neuroendocrine site that produces numerous hemolymph-borne agents including the most complex class of endocrine signaling molecules—neuropeptides. Via a multifaceted mass spectrometry (MS) approach, 70 neuropeptides were identified including orcokinins, orcomyotropin, crustacean hyperglycemic hormone (CHH) precursor-related peptides (CPRPs), red pigment concentrating hormone (RPCH), pigment dispersing hormone (PDH), proctolin, RFamides, RYamides, and HL/IGSL/IYRamide. Among them, 15 novel orcokinins, 9 novel CPRPs, one novel orcomyotropin, one novel Ork/Orcomyotropin-related and one novel PDH were de novo sequenced via collision induced dissociation (CID) from the SG of a model organism Callinectes sapidus. Electron transfer dissociation (ETD) was used for sequencing of intact CPRPs due to their large size and charge state. Capillary isoelectric focusing (CIEF) was employed for separation of members of the orcokinin family which is one of the most abundant neuropeptide families observed in the SG. Collectively, our study represents the most complete characterization of neuropeptides of the SG and provides a foundation for future investigation of the physiological function of neuropeptides in the SG of C. sapidus.
Coupling capillary electrophoresis (CE) based separation techniques to mass spectrometry creates a powerful platform for analysis of a wide range of biomolecules from complex samples because it combines the high separation efficiency of CE and the sensitivity and selectivity of MS detection. ESI and MALDI, as the most common soft ionization techniques employed for CE and MS coupling, offer distinct advantages for biomolecular characterization. This review is focused primarily on technological advances in combining CE and chip-based CE with ESI and MALDI MS detection in the past five years. Selected applications in the analyses of metabolites, peptides, and proteins with the recently developed CE-MS platforms are also highlighted.
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