Impact of peptide modifications on the isobaric tags for relative and absolute quantitation method accuracy.

摘要: In this study, the impact of amino acid modifications on accuracy iTRAQ (isobaric tags for relative and absolute quantitation) method was evaluated. MCF-7 breast cancer cells, cultured in presence 17β-estradiol tamoxifen, were used as a model system. The cells labeled analyzed by reversed-phase liquid chromatography pulsed Q dissociation ion trap tandem mass spectrometry detection. Database searching performed using various combinations modification allowances, i.e, Lys/Tyr/Cys terminal labeling, Lys methylation, acetylation carbamylation, Cys/Met oxidation. Other than intended Lys/amino such occur result either enzymatic or sample preparation related reactions are typically ignored quantitation analysis to minimize rate false-positive peptide identifications. study revealed that with greatest protein identification quantit...