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Cited by 253

The DOI matches its Crossref record; 23 of the 23 references it cites were found in a registry or an index.

Absolute Quantification of the Model Biomarker Prostate-Specific Antigen in Serum by LC−MS/MS Using Protein Cleavage and Isotope Dilution Mass Spectrometry

Barnidge, David R., Goodmanson, Marcia K., Klee, George G., Muddiman, David C.·2004·Journal of Proteome Research
DOI 10.1021/pr049963d
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Abstract

Protein cleavage-isotope dilution mass spectrometry (PC-IDMS) can be used to quantify proteins, with an isotope-labeled analogue of the peptide fragment used as an internal standard. Here, we investigate use of a standard LC-MS/MS platform for quantifying a model biomarker directly from serum by this technique. We synthesized a peptide (IVGGWECEK) identical to the N-terminal tryptic fragment of PSA but with each glycine containing two 13C atoms and one 15N atom. PSA-free human serum was denatured with urea followed by the introduction of PSA standard and the stable isotope labeled internal standard peptide. The sample was then proteolyzed with trypsin and subjected to quantification using LC-MS/ MS on a triple quadrupole mass spectrometer. A linear least squares calibration curve made from five different concentrations of PSA added to serum and digested (each made in triplicate and randomly injected three times) had a mean slope of 0.973 (SE = 0.023), intercept of -0.003 (SE = 0.022), and R2 of 0.971. Recovery of calibrators ranged from 70 to 85% with a mean run-to-run CV of 13% and a mean within-run CV of 5.7%. PC-IDMS is a promising technique for quantifying proteins covering a broad range of applications from standardizing immunoassays to monitoring post-translational modifications to quantifying newly discovered biomarkers prior to the development and implementation of an immunoassay, just to name a few. Issues surrounding the application of PC-IDMS for the absolute quantification of proteins include selection of a proteolytic fragment for quantification that can be cleaved and isolated reproducibly over a broad dynamic range, stable isotope labeled synthetic peptide standards that give consistent results, and LC-MS/MS methods that provide adequate sensitivity and reproducibility without creating impractical analysis times. The results presented here show that absolute quantification can be performed on the model biomarker PSA introduced into denatured serum when analyzed by LC-MS/MS. However, concerns still exist regarding sensitivity compared to existing immunoassays as well as the reproducibility of PC-IDMS performed in different matrixes.

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Metadata

Authors
Barnidge, D. R., Goodmanson, M. K., Klee, G. G., & Muddiman, D. C.
Venue
Journal of Proteome Research
Publisher
American Chemical Society (ACS)
Published
2004-04-13
Volume
3
Issue
3
Pages
644-652
ISSN
  • 1535-3893 (ISSN-L)
  • 1535-3907
DOI
10.1021/pr049963d
OpenAlex
W2010079667
Cited by
253
References
23
FWCI
5.93
Type
journal article
Language
en
Open access
closed

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