title: Characterisation of major peptides in 'jack jumper' ant venom by mass spectrometry.
abstract: The jack jumper ant, Myrmecia pilosula, is endemic to South-Eastern Australia, where around 2.7% of the population has a history of systemic allergic reactions (anaphylaxis) to its venom. Previous work had indicated that there were several allergenic peptides derived from the cDNA Myr p 1, the major expressed allergenic product being a 56-residue peptide (Myr p 1 57-->112, 'pilosulin 1', approximately 6052 Da). Another major allergen had been described as a 27 residue peptide derived from the cDNA Myr p 2 (Myr p 2 49-->75, 'pilosulin 2', approximately 3212 Da), possibly existing as part of a disulfide complex. As a preliminary step in detailed stability studies of a pharmaceutical product used for venom immunotherapy, LC-MS and Edman sequencing analysis of venom collected from various locations by both electrical stimulation and venom sac dissection was undertaken. More than 50 peptides in the 4-9 kDa range were detected in LC-MS analyses. A subsequence of Myr p 2 was found as part of the major peptide present in all samples; this was a bis-disulphide linked, antiparallel aligned heterodimer consisting of Myr p 2 49-->74, (des-Gly(27)-pilosulin 2, approximately 3155 Da) and a previously unreported peptide of approximately 2457 Da. Pilosulin 1 was found by a combination of tandem mass spectrometry and Edman sequencing to exist mainly, and sometimes exclusively, as a previously unreported approximately 6067 Da variant, in which the valine at residue 5 is replaced by isoleucine. A range of hydrolysis products of [Ile(5)]pilosulin 1 and pilosulin 1 were also detected in partially degraded venom. Further IgE-binding studies using these peptides are warranted and a revision of the nomenclature of allergenic components of M. pilosula venom may be required to conform with established IUIS guidelines.
authors.affiliation: Central Science Laboratory, University of Tasmania, Private Bag 74, Hobart 7001, Tasmania, Australia. noel.davies@utas.edu.au
authors.forename: Noel W
authors.initials: NW
authors.lastname: Davies
authors.forename: Michael D
authors.initials: MD
authors.lastname: Wiese
authors.forename: Simon G A
authors.initials: SG
authors.lastname: Brown
mesh_terms: D000485:Allergens / Q000737:chemistry*; D000595:Amino Acid Sequence; D000818:Animals; D000862:Ant Venoms / Q000737:chemistry* / Q000302:isolation & purification; D001000:Ants / Q000737:chemistry*; D001315:Australia; D002853:Chromatography, Liquid; D019476:Insect Proteins / Q000737:chemistry*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009943:Organophosphorus Compounds; D010455:Peptides / Q000302:isolation & purification*; D020539:Sequence Analysis, Protein
chemical_list: C043517:2-(4-isothiocyanatophenoxy)-1,3,2-dioxaphosphinene 2-oxide; D000485:Allergens; D000862:Ant Venoms; D019476:Insect Proteins; C079435:Myr p I; C096132:Myr p II protein, Myrmecia pilosula; D009943:Organophosphorus Compounds; D010455:Peptides; C115595:pilosulin 1