title: RP-HPLC-ESI-MS characterization of novel peptide fragments related to rat parotid secretory protein in parasympathetic induced saliva.
abstract: Two peptides (MW 1211.7 and 928.5 Da) were detected by RP-HPLC-ESI-MS analysis of parotid saliva secreted upon continuous parasympathetic stimulation. The peptide with the higher mass (PSPFr-A) corresponded to the N-terminal dodecapeptide (Fragment 1-12) of rat parotid secretory protein (PSP), while the peptide with the lower mass (PSPFr-B) corresponded to the 4-12 fragment of the same protein. During stimulation, the PSPFr-A secretion increased, while the PSPFr-B secretion decreased (HPLC-ESI-MS). In the presence of cycloheximide, PSPFr-A was not demonstrated, while the PSPFr-B secretion decreased. In the presence of aprotinin, the PSPFr-B secretion was almost abolished, while the PSPFr-A secretion increased to higher levels than those observed in the absence of the inhibitor. In vitro perfusion, with artificial solution, of stimulated rat parotid glands excluded that the fragments were derived from the circulation. Neither peptide occurred in enriched granule preparations from unstimulated glands. The results suggest that at least two pathways--granular and vesicular--are responsible for the generation of the two peptides. PSPFr-A is the first cleavage product in both pathways. PRPFr-B is probably generated from granular PSPFr-A only and, at the end of the granule mediated pathway, by the action of an enzyme of the serine protease class.
authors.affiliation: Section of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Göteborg, Sweden. jorgen.ekstrom@pharm.gu.se
authors.forename: Jörgen
authors.initials: J
authors.lastname: Ekström
authors.forename: Masataka
authors.initials: M
authors.lastname: Murakami
authors.forename: Rosanna
authors.initials: R
authors.lastname: Inzitari
authors.forename: Nina
authors.initials: N
authors.lastname: Khosravani
authors.forename: Chiara
authors.initials: C
authors.lastname: Fanali
authors.forename: Tiziana
authors.initials: T
authors.lastname: Cabras
authors.forename: Junko
authors.initials: J
authors.lastname: Fujita-Yoshigaki
authors.forename: Hiorshi
authors.initials: H
authors.lastname: Sugiya
authors.forename: Irene
authors.initials: I
authors.lastname: Messana
authors.forename: Massimo
authors.initials: M
authors.lastname: Castagnola
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D007611:Aprotinin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D003513:Cycloheximide / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D008297:Male; D008969:Molecular Sequence Data; D010275:Parasympathetic Nervous System / Q000502:physiology*; D010306:Parotid Gland / Q000737:chemistry / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010446:Peptide Fragments / Q000032:analysis* / Q000235:genetics; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D012463:Saliva / Q000737:chemistry / Q000378:metabolism; D012471:Salivary Proteins and Peptides / Q000032:analysis* / Q000235:genetics; D022142:Secretory Vesicles / Q000737:chemistry; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: C511598:Bpifa2 protein, rat; D010446:Peptide Fragments; D011500:Protein Synthesis Inhibitors; D012471:Salivary Proteins and Peptides; D015842:Serine Proteinase Inhibitors; D007611:Aprotinin; D003513:Cycloheximide