assayexpress™
The service for development of protein biomarker assays

• Let us develop all the biomarkers on your list. No need to reduce the list from your biomarker discovery efforts.
• No need for antibodies for our assay development platform

Features of assayexpress™

• Mass spectrometry-based assay development
• Assay development for many proteins can be done simultaneously
• Optimized for multiplexing, short run times and lowest sample requirement
• Quantification is not dependent on affinity reagents
• Absolute and relative quantification
• Assay development time is weeks to months
• Easily tailored across species
• Empirical selection of peptides for MRM assay
• High specificity for targeted protein(s) including post-translational modifications and isoforms
• Assays validated for LOD, LOQ, analytic, technical and biological variation

View the assayexpress™ overview - PDF

Browse through the biomarkerlibrary™ and design your own biomarker panel.

Browse by sample type
Human plasma - 440 proteins - PDF
Human cerebral spinal fluid (CSF) - 850 proteins - PDF
Human urine - 894 proteins - PDF
THP1 cell line - 3409 proteins - PDF
A549 cell line - 3336 proteins - PDF
MelJuso melanoma cell line - 3366 - PDF
Rat liver - 2209 proteins - PDF

Multiple Reaction Monitoring (MRM) is a mass spectrometry-based assay historically used for small molecule quantitation. Whereas an intact protein is too large for MRM, proteolytically generated peptides can easily be measured. There are three key steps in developing a protein assay using the MRM technique.

Selection of Peptides. Typically 2 to 3 peptides are selected from experimental data as surrogates for each of the targeted proteins. The selected peptides possess unique sequences and fragment ion signatures to achieve specificity.

MRM Assay Testing. Candidate peptides are tested in the relevant sample. Chromatographic and mass spectrometer conditions are optimized so that the targeted proteins can be monitored with the least amount of sample and the shortest assay run time. Sample preparation conditions are optimized as necessary to observe lower abundance proteins.

Protein Quantitation. The MRM approach can be used to yield absolute or relative protein biomarker quantitation data. Heavy isotope labeled peptide standards are used for absolute quantitation. Calibration curves are constructed based on the ratio of the labeled and unlabeled peptides in a complex matrix representative of the samples. Intra-assay reproducibility is established.

Selected publications on peptide MRM

• Peptide standard use for absolute quantification.
  - Gerber, Rush, Stemman, Kirschner, Gygi, (2003)
  - Absolute quantification of proteins and phosphoproteins from cell lysates by tandem MS, PNAS 100: 6940-5
  


• Enrichment strategy for low abundance proteins in biofluids
  - Anderson, Anderson, Haines, Hardie, Olafson, Pearson, (2004), Mass spectrometric quantification of peptides and proteins using Stable Isotope Standards and Capture by AntiPeptide Antibodies (SISCAPA), JPR 3: 235-44


• Synthetic concatenated peptide standards for multiplexing assays
  - Benynon, Doherty, Pratt, Gaskell, (2005), Multiplexed absolute quantification in proteomics using artificial QCAT proteins or concatenated signature peptides, Nat Methods 2: 587-9


• Platform demonstration.
  - Anderson, Hunter, 2006, Quantitative mass spectrometric multiple reaction monitoring assays for major plasma proteins, MCP 5: 573-88
  - Keshishian, Addona, Burgess, Kuhn, Carr, 2007, Quantitative, multiplexed assays for low abundance proteins in plasma by targeted mass spectrometry and stable isotope dilution, MCP 6: 2212-29

Latest News

NextGen Sciences strengthens protein biomarker team with two key appointments
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New! Biomarkers

NextGen Sciences now offers protein biomarker assay development and monitoring solutions
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Join NextGen Sciences at the Cancer Diagnostics: Next Generation Technologies on the 21st - 22nd August 2008, Washington, DC
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