title: A hemoglobin fragment found in cervicovaginal fluid from women in labor potentiates the action of agents that promote contraction of smooth muscle cells.
abstract: We employed a proteomic approach to search for peptides that have a physiological role in labor. Cervicovaginal secretions were collected at term from women in labor and women at term not in labor. Samples were spotted onto weak cation exchange chips (WCX-2) and analyzed using Surface-Enhanced Laser Desorption Ionization Time-of-Flight Mass Spectrometry (SELDI-TOF-MS). Spectra were obtained for each sample and Biomarker Wizard analysis revealed 25 peaks that had significantly different peak intensity between the labor and non-laboring women. The sequences of five peaks that were significantly elevated in the labor cohort were determined using Protein Chip Interface Quadruple Time-of-Flight Mass Spectrometry (PCI-QTOF-MS). All of these peaks were identified as fragments of alpha or beta-hemoglobin (Hb). A 2.022 kDa fragment of alpha-Hb (amino acids 110-128, NH2-AAHLPAEFTPAVHASLDKF-COOH) was found to potentiate smooth muscle cell contraction in response to bradykinin, oxytocin and prostaglandin-F2alpha. This peptide may promote vasoconstriction and augment normal labor through enhancing the action of uterotonins.
authors.affiliation: Center for Research on Reproduction and Women's Health, University of Pennsylvania Medical School, Biomedical Research Building II/III, 421 Curie Blvd., Philadelphia, PA 19104, USA. aegreen@mail.med.upenn.edu
authors.forename: Amy G
authors.initials: AG
authors.lastname: Brown
authors.forename: Rita S
authors.initials: RS
authors.lastname: Leite
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Engler
authors.forename: Dennis E
authors.initials: DE
authors.lastname: Discher
authors.forename: Jerome F
authors.initials: JF
authors.lastname: Strauss
mesh_terms: D000595:Amino Acid Sequence; D001826:Body Fluids / Q000378:metabolism*; D005260:Female; D006454:Hemoglobins / Q000737:chemistry*; D006801:Humans; D007743:Labor, Obstetric / Q000378:metabolism*; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000378:metabolism / Q000473:pathology*; D010446:Peptide Fragments / Q000737:chemistry; D011247:Pregnancy; D014590:Uterine Contraction; D014621:Vagina / Q000473:pathology*; D014661:Vasoconstriction
chemical_list: D006454:Hemoglobins; D010446:Peptide Fragments; C070077:alpha(A) globin