Frequently Asked Questions
What is SRM?
Selective Reaction Monitoring (SRM) is a targeted mass spectrometry assay format that enables absolute biomarker quantitation.
Why should I choose a SRM assay over a TMT®SRM assay for candidate biomarker validation?
We recommend a classical SRM assay for:
- Absolute biomarker quantitation
- A bespoke list of candidates generated from the literature a biomarker discovery project that did not use TMT®
- A bespoke list of post-translational modifications on particular protein(s)
- Customers looking to obtain specific measurements of endogenous as well as transgene proteins in pre-clinical models.
Why should I choose a SRM assay over an antibody based method for candidate biomarker validation?
SRM is particularly suited to the measurement of candidates that do not have commercially available antibodies especially post-translational modifications, protein isoforms and species specific proteins.
How many proteins can be included in a SRM Assay?
SRM assays are typically developed for 5-50 biomarker candidates.
What are the stages of SRM Assay Development?
There are six stages in the SRM Assay Development process:
- Phase 1 - Selection of proteotypic peptides
- Phase 2 - Ordering AQUA peptides (if required)
- Phase 3 - SRM assay development and validation
- Phase 4 - Optimization of sample preparation (if required)
- Phase 5 - Biomarker qualification in small cohort
- Phase 6 - Biomarker validation in larger cohort
What types of sample can be analyzed using a SRM assay?
All sample types including cell and tissue lysates and body fluids such as CSF and plasma across all therapeutic areas can be analyzed in a SRM Assay.
What performance characteristics are defined during TMT ® SRM assay development?
LOD, LOQ, precision and linear working range.
What type of mass spectrometry is used for a SRM study?
SRM Assays are developed and ran on a UHPLC-TSQ Vantage Triple Stage Quadrupole LC/MS Mass Spectrometer from ThermoScientific.
What does the SRM data output look like?
Quantitative values for each analyte are provided normally in a simple spreadsheet format.
What additional bioinformatics and data interpretation packages are available for a SRM study?
- PS offers its SRM customers a biostatistics consultancy service.
- As a consultancy service the details and outputs are discussed with our customers on a case by case basis, to meet the needs of the customer and are typically charged at a daily rate.