title: Mass spectrometric characterization and physiological actions of novel crustacean C-type allatostatins.
abstract: The crustacean stomatogastric ganglion (STG) is modulated by numerous neuropeptides that are released locally in the neuropil or that reach the STG as neurohormones. Using 1,5-diaminonaphthalene (DAN) as a reductive screening matrix for matrix-assisted laser desorption/ionization (MALDI) mass spectrometric profiling of disulfide bond-containing C-type allatostatin peptides followed by electrospray ionization quadrupole time-of-flight (ESI-Q-TOF) tandem mass spectrometric (MS/MS) analysis, we identified and sequenced a novel C-type allatostatin peptide (CbAST-C1), pQIRYHQCYFNPISCF-COOH, present in the pericardial organs of the crab, Cancer borealis. Another C-type allatostatin (CbAST-C2), SYWKQCAFNAVSCFamide, was discovered using the expressed sequence tag (EST) database search strategy in both C. borealis and the lobster, Homarus americanus, and further confirmed with de novo sequencing using ESI-Q-TOF tandem MS. Electrophysiological experiments demonstrated that both CbAST-C1 and CbAST-C2 inhibited the frequency of the pyloric rhythm of the STG, in a state-dependent manner. At 10(-6)M, both peptides were only modestly effective when initial frequencies of the pyloric rhythm were >0.8Hz, but almost completely suppressed the pyloric rhythm when applied to preparations with starting frequencies <0.7Hz. Surprisingly, these state-dependent actions are similar to those of the structurally unrelated allatostatin A and allatostatin B families of peptides.
authors.affiliation: School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison, 777 Highland Avenue, Madison, WI 53705-2222, USA.
authors.forename: Mingming
authors.initials: M
authors.lastname: Ma
authors.forename: Theresa M
authors.initials: TM
authors.lastname: Szabo
authors.forename: Chenxi
authors.initials: C
authors.lastname: Jia
authors.forename: Eve
authors.initials: E
authors.lastname: Marder
authors.forename: Lingjun
authors.initials: L
authors.lastname: Li
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000595:Amino Acid Sequence; D000825:Animal Structures / Q000737:chemistry; D000818:Animals; D003386:Brachyura / Q000737:chemistry; D001923:Brain Chemistry; D003445:Crustacea / Q000737:chemistry*; D030562:Databases, Protein; D004305:Dose-Response Relationship, Drug; D005724:Ganglia / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D008121:Nephropidae / Q000737:chemistry; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009479:Neuropeptides / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology*; D011708:Pylorus / Q000187:drug effects / Q000294:innervation / Q000502:physiology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D009479:Neuropeptides