title: Mass spectrometric detection of CP4 EPSPS in genetically modified soya and maize.
abstract: The potential of protein fractionation hyphenated to mass spectrometry (MS) to detect and characterize the transgenic protein present in Roundup Ready soya and maize has been investigated. Genetically modified (GM) soya and maize contain the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene from Agrobacterium tumefaciens CP4, which confers resistance to the herbicide glyphosate. The GM soya and maize proteomes were fractionated by gel filtration, anion-exchange chromatography and sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) prior to MS. This facilitated detection of a tryptic peptide map of CP4 EPSPS by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS and nanoelectrospray ionization quadrupole time-of-flight (nanoESI-QTOF) MS. Subsequently, sequence information from the CP4 EPSPS tryptic peptides was obtained by nanoESI-QTOF MS/MS. The identification was accomplished in 0.9% GM soya seeds, which is the current EU threshold for food-labeling requirements.
authors.affiliation: Centre for Chemical and Bioanalytical Sciences, Royal Holloway, University of London, Egham TW20 0EX, UK.
authors.forename: Mireia Fernández
authors.initials: MF
authors.lastname: Ocaña
authors.forename: Paul D
authors.initials: PD
authors.lastname: Fraser
authors.forename: Raj K P
authors.initials: RK
authors.lastname: Patel
authors.forename: John M
authors.initials: JM
authors.lastname: Halket
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bramley
mesh_terms: D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase / Q000032:analysis / Q000737:chemistry* / Q000235:genetics*; D000595:Amino Acid Sequence; D005504:Food Analysis / Q000379:methods; D005515:Food Labeling / Q000379:methods; D005819:Genetic Markers / Q000235:genetics; D008969:Molecular Sequence Data; D010449:Peptide Mapping / Q000379:methods*; D030821:Plants, Genetically Modified / Q000378:metabolism*; D011994:Recombinant Proteins / Q000032:analysis / Q000737:chemistry; D012680:Sensitivity and Specificity; D013025:Glycine max / Q000502:physiology*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D003313:Zea mays / Q000502:physiology*
chemical_list: D005819:Genetic Markers; D011994:Recombinant Proteins; D051229:3-Phosphoshikimate 1-Carboxyvinyltransferase