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An accurate proteomic quantification method: Fluorescence labeling absolute quantification ( FLAQ ) using multidimensional liquid chromatography and tandem mass spectrometry
Author(s) -
Liu Junyan,
Liu Yang,
Gao Mingxia,
Zhang Xiangmin
Publication year - 2012
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/pmic.201100649
Subject(s) - chemistry , chromatography , tandem mass spectrometry , fluorescence , quantitative proteomics , label free quantification , detection limit , mass spectrometry , proteome , liquid chromatography–mass spectrometry , trypsin , proteomics , biochemistry , enzyme , physics , quantum mechanics , gene
A facile proteomic quantification method, fluorescent labeling absolute quantification ( FLAQ ), was developed. Instead of using MS for quantification, the FLAQ method is a chromatography‐based quantification in combination with MS for identification. Multidimensional liquid chromatography ( MDLC ) with laser‐induced fluorescence ( LIF ) detection with high accuracy and tandem MS system were employed for FLAQ . Several requirements should be met for fluorescent labeling in MS identification: Labeling completeness, minimum side‐reactions, simple MS spectra, and no extra tandem MS fragmentations for structure elucidations. A fluorescence dye, 5‐iodoacetamidofluorescein, was finally chosen to label proteins on all cysteine residues. The fluorescent dye was compatible with the process of the trypsin digestion and MALDI MS identification. Quantitative labeling was achieved with optimization of reacting conditions. A synthesized peptide and model proteins, BSA (35 cysteines), OVA (five cysteines), were used for verifying the completeness of labeling. Proteins were separated through MDLC and quantified based on fluorescent intensities, followed by MS identification. High accuracy ( RSD % < 1.58) and wide linearity of quantification (1–10 5 ) were achieved by LIF detection. The limit of quantitation for the model protein was as low as 0.34 amol. Parts of proteins in human liver proteome were quantified and demonstrated using FLAQ .