Selected reaction monitoring (SRM) mass spectrometry without isotope labeling can be used for rapid protein quantification

Wenbo Zhi, Meiyao Wang, Jin-Xiong She

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


The validation of putative biomarker candidates has become the major bottle-neck in protein biomarker development. Conventional immunoaffinity methods are limited by the availability of antibodies and kits. Here we demonstrate the feasibility of using selected reaction monitoring (SRM) without isotope labeling to achieve fast and reproducible quantification of serum proteins. The SRM/MRM assays for three standard serum proteins, including ceruloplasmin (CP), serum aymloid A (SAA) and sex hormone binding globulin (SHBG), have good linear ranges, generally 103 to 104. There are almost perfect correlations between SRM intensities and the loaded peptide amounts (R2 is usually ∼0.99). Our data suggest that SRM/MRM is able to quantify proteins within the range of 0.2-2 fmol, which is comparable to the commercial ELISA/LUMINEX kits for these proteins. Excellent correlations between SRM/MRM and ELISA/LUMINEX assays were observed for SAA and SHBG (R2 = 0.928 and 0.851, respectively). However, the correlation between SRM/MRM and ELISA for CP is less desirable (R2 = 0.565). The reproducibility for SRM/MRM assays is generally very good but may depend on the proteins/peptides being analyzed (R2 = 0.931 and 0.882 for SAA and SHBG, and 0.723 for CP). The SRM/MRM assay without isotope labeling is a rapid and useful method for protein biomarker validation in a modest number of samples and is especially useful when other assays such as ELISA or LUMINEX are not available.

Original languageEnglish (US)
Pages (from-to)1583-1588
Number of pages6
JournalRapid Communications in Mass Spectrometry
Issue number11
StatePublished - Jun 15 2011

ASJC Scopus subject areas

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry


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