Document Detail

Impact of peptide modifications on the isobaric tags for relative and absolute quantitation method accuracy.
MedLine Citation:
PMID:  21210697     Owner:  NLM     Status:  MEDLINE    
In this study, the impact of amino acid modifications on the accuracy of the iTRAQ (isobaric tags for relative and absolute quantitation) method was evaluated. MCF-7 breast cancer cells, cultured in the presence of 17β-estradiol and tamoxifen, were used as a model system. The cells were labeled and analyzed by reversed-phase liquid chromatography and pulsed Q dissociation ion trap tandem mass spectrometry detection. Database searching was performed by using various combinations of amino acid modification allowances, i.e, Lys/Tyr/Cys and amino terminal iTRAQ labeling, Lys methylation, acetylation and carbamylation, and Cys/Met oxidation. Other than the intended Lys/amino terminal iTRAQ labeling, such modifications occur as a result of either enzymatic or sample preparation related reactions and are typically ignored in quantitation analysis to minimize the rate of false-positive peptide identifications. The study revealed that the modifications with the greatest impact on protein identification and quantitation pertain to Lys and Tyr amino acid residues, that by enabling such modifications the number and type of identified proteins will change (by up to 10%), and that the rate of false-positive protein identifications can be maintained below an upper threshold of 5% if appropriate data filtering conditions are used. In addition, the interference of possible posttranslational modifications (i.e., phosphorylation) with iTRAQ quantitation was examined.
Milagros J Tenga; Iulia M Lazar
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2011-01-06
Journal Detail:
Title:  Analytical chemistry     Volume:  83     ISSN:  1520-6882     ISO Abbreviation:  Anal. Chem.     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-01-31     Completed Date:  2011-05-17     Revised Date:  2013-07-24    
Medline Journal Info:
Nlm Unique ID:  0370536     Medline TA:  Anal Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  701-7     Citation Subset:  IM    
Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
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MeSH Terms
Amino Acid Sequence
Amino Acids / analysis
Cell Line, Tumor
Chromatography, Reverse-Phase / methods*
Mass Spectrometry / methods*
Molecular Sequence Data
Peptides / chemistry*
Protein Processing, Post-Translational
Proteins / chemistry
Grant Support
R21 CA126669-01A1/CA/NCI NIH HHS; R21-CA126669-01A1/CA/NCI NIH HHS
Reg. No./Substance:
0/Amino Acids; 0/Peptides; 0/Proteins

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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