A method for selective enrichment and analysis of nitrotyrosine-containing peptides in complex proteome samples

Elevated levels of protein tyrosine nitration have been found in various neurodegenerative diseases and age-related pathologies. Until recently, however, the lack of an efficient enrichment method has prevented the analysis of this important low-level protein modification. We have developed a method...

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Bibliographic Details
Published in:Journal of proteome research Vol. 6; no. 6; p. 2257
Main Authors: Zhang, Qibin, Qian, Wei-Jun, Knyushko, Tatyana V, Clauss, Therese R W, Purvine, Samuel O, Moore, Ronald J, Sacksteder, Colette A, Chin, Mark H, Smith, Desmond J, Camp, 2nd, David G, Bigelow, Diana J, Smith, Richard D
Format: Journal Article
Language:English
Published: United States 01.06.2007
Subjects:
Amino Acid Sequence
Animals
Brain Chemistry
Cattle
Chromatography, Liquid
Humans
Mass Spectrometry
Mice
Molecular Sequence Data
Peptides - chemistry
Proteins - chemistry
Proteome - chemistry
Proteomics - methods
Tyrosine - analogs & derivatives
Tyrosine - analysis
ISSN:1535-3893
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Summary:Elevated levels of protein tyrosine nitration have been found in various neurodegenerative diseases and age-related pathologies. Until recently, however, the lack of an efficient enrichment method has prevented the analysis of this important low-level protein modification. We have developed a method that specifically enriches nitrotyrosine-containing peptides so that both nitrotyrosine peptides and specific nitration sites can be unambiguously identified with LC-MS/MS. The procedure consists of the derivatization of nitrotyrosine into free sulfhydryl groups followed by high efficiency enrichment of sulfhydryl-containing peptides with thiopropyl sepharose beads. The derivatization process includes: (1) acetylation with acetic anhydride to block all primary amines, (2) reduction of nitrotyrosine to aminotyrosine, (3) derivatization of aminotyrosine with N-Succinimidyl S-Acetylthioacetate (SATA), and (4) deprotection of S-acetyl on SATA to form free sulfhydryl groups. The high specificity of this method is demonstrated by the contrasting percentage of nitrotyrosine-derivatized peptides in the identified tandem mass spectra between enriched and unenriched samples. Global analysis of unenriched in vitro nitrated human histone H1.2, bovine serum albumin (BSA), and mouse brain homogenate samples had 9%, 9%, and 5.9% of identified nitrotyrosine-containing peptides, while the enriched samples had 91% , 62%, and 35%, respectively. Duplicate LC-MS/MS analyses of the enriched mouse brain homogenate identified 150 unique nitrated peptides covering 102 proteins with an estimated 3.3% false discovery rate.
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ISSN:1535-3893
DOI:10.1021/pr0606934