Jun 4, 2014 - enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) was labeled using a ... of CP4 EPSPS was performed using matrix-assisted laser.
Anal Bioanal Chem DOI 10.1007/s00216-014-7965-7
RESEARCH PAPER
Quantification of genetically modified soya using strong anion exchange chromatography and time-of-flight mass spectrometry Po-Chih Chang & P. Muralidhar Reddy & Yen-Peng Ho
Received: 9 April 2014 / Revised: 4 June 2014 / Accepted: 11 June 2014 # Springer-Verlag Berlin Heidelberg 2014
Abstract Stable-isotope dimethyl labeling was applied to the quantification of genetically modified (GM) soya. The herbicide-resistant gene-related protein 5enolpyruvylshikimate-3-phosphate synthase (CP4 EPSPS) was la bele d usin g a dime thyl la belin g rea gen t, formaldehyde-H2 or -D2. The identification and quantification of CP4 EPSPS was performed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The CP4 EPSPS protein was separated from high abundance proteins using strong anion exchange chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Then, the tryptic peptides from the samples and reference were labeled with formaldehyde-H2 and formaldehyde-D2, respectively. The two labeled pools were mixed and analyzed using MALDI-MS. The data showed a good correlation between the peak ratio of the H- and D-labeled peptides and the GM soya percentages at 0.5, 1, 3, and 5 %, with R2 of 0.99. The labeling reagents are readily available. The labeling experiments and the detection procedures are simple. The approach is useful for the quantification of GM soya at a level as low as 0.5 %. Keywords Genetically modified soya . Dimethyl labeling reagent . Matrix-assisted laser desorption/ionization mass spectrometry . Quantification . Anion exchange chromatography Electronic supplementary material The online version of this article (doi:10.1007/s00216-014-7965-7) contains supplementary material, which is available to authorized users. P.
