Quantitative analysis of proteins is essential for modern proteomics. We have thus far reported methodologies for the relative quantitative analysis of proteins and peptides with the use of combinations of stable isotope-labeled and unlabeled small organic molecules that react with specific amino acid residues combined with soft ionization mass spectrometry, such as matrix-assisted laser dissorption/ionization (MALDI) or electrospray ionization (ESI) by a so-called �shotgun approach.� Here, the combination of the cysteine-specific modifiers we reported previously, iodoacetanilide (IAA) and 13C7-labeled iodoacetanilide (13C7-IAA), was applied to the absolute quantification of proteins. The selected reaction monitoring (SRM) with the use of nano liquid chromatography/nanoelectrospray ionization ion trap mass spectrometry (nano LC/nano-ESI-IT-MS) analysis was applied to the precise quantification of three commercial proteins. Good correlation was observed between the theoretical ratios and observed ratios for all these proteins. Due to efficient tagging, this method does not require separate synthesis of isotope-labeled peptides for the SRM studies unlike most other existing SRM studies. This method was also found to be effective for precise quantification of proteins even in a complex protein environment, such as in the clinical sample of nipple discharges. Therefore, this method is expected to be a useful tool for proteomics research.

Quantification of proteins using <sup>13</sup>C<sub>7</sub>-labeled and unlabeled iodoacetanilide by nano liquid chromatography/nanoelectrospray ionization and by selected reaction monitoring mass spectrometry

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.

Quantification of proteins using 13C7-labeled and unlabeled iodoacetanilide by nano liquid chromatography/nanoelectrospray ionization and by selected reaction monitoring mass spectrometry

Quantification of proteins using ¹³C₇-labeled and unlabeled iodoacetanilide by nano liquid chromatography/nanoelectrospray ionization and by selected reaction monitoring mass spectrometry