Use of DNA-Aptamers for Enrichment of Low Abundant Proteins in Cellular Extracts for Quantitative Detection by Selected Reaction Monitoring

Abstract

The relationship between the amount of a target protein in a complex biological sample and its amount measured by selected reaction monitoring (SRM) mass spectrometry upon the affinity enrichment of the target protein with aptamers immobilized on a solid phase has been investigated. Human thrombin added in known concentrations to cellular extracts derived from bacterial cells was used as a model target protein. The affinity enrichment of thrombin in cellular extracts by means of the thrombin-binding aptamer immobilized on the surface of magnetic microbeads resulted in an approximately 10-fold increase of the concentration of the target protein and a 100-fold decrease of the low limit of a target protein concentration range where its quantitative detection by SRM was possible without interference from other peptides present in the tryptic digest.