The rapidly expanding field of proteomics is changing the way we understand cellular function, and paving the path for new diagnostics and medicines each day. The proteomics industry is projected to expand at a rate of 19% per year to a market value of approximately $12B by 2019, making it one of the fastest growing scientific markets in the world. As the medical and pharmaceutical fields attempt to integrate standardized proteomics experiments into diagnostic and drug discovery pipelines, there is a great need for robust methods for absolute quantification of high value protein targets, as their expression levels in cells are often markers of disease or the function of a drug or drug candidate. To this end, we have developed a new method for absolute quantification of target proteins within cell lysates. Although methods for absolute quantification are already being employed, our technology saves considerably on experimental cost and provides more robust measurement and on-the-fly cross-validation, as it relies on both internal and external standards for quantitative measurements.
Indirect Calibration Increases Control of Experimental Variables While Cutting Costs
Current methods for absolute quantification of proteins rely on spiking an isotopically labeled protein or peptide surrogate into the sample prior to analysis via mass spectrometry. These techniques allow direct comparison between the intensities of unknown (unlabeled) and known(labeled) peptide signals, however do not account for errors in the sample processing, which may result in differential losses of certain peptides. Moreover, the cost of isotopically labeled media can be restrictive when expressing labeled protein standards for in-proteome quantification. Our method corrects for experimental processing errors while cutting costs by utilizing an isotopically labeled reference proteome, calibrated against an unlabeled protein standard. This method saves substantial costs due to the lower volume of media required to grow samples for proteome analysis than for protein expression and purification. After accurate calibration of the isotopically labeled reference proteome, reference proteome can be mixed with an experimental sample and proteins of interest can be quantified based on the ratios between isotopic pairs. We found this method increases accuracy and day-to-day precision in targeted quantitative proteomics, a major hurdle for the integration of proteomics into diagnostic and drug discovery workflows.
- Protein quantification across a wide range of analytes
- Functional assays of small molecule drugs candidates
- Diagnostic analysis of patient proteomes
- Accounts for experimental variables
- Cost savings on isotopically labeled media
- High potential for multiplex analysis