title: An evaluation of an aptamer for use as an affinity reagent with MS: PCSK9 as an example protein.
abstract: BACKGROUND
  For quantitative immunoaffinity IA-LC-MS, the utility of antibodies has been demonstrated many times but the utility of aptamers as affinity reagents is unproven.
  
  
  METHODS
  Immunoaffinity reagents including a monoclonal antibody and an aptamer were coupled to magnetic beads and used as part of an enrichment strategy for PCSK9 quantitation in plasma.
  
  
  RESULTS
  With limited method development, we have established a comparison of an anti-PCSK9 aptamer with an anti-PCSK9 monoclonal antibody. The background that results from a tryptic digest of affinity enrichment in plasma was demonstrated for each reagent using high-resolution full scan MS. The assay recovery was demonstrated for multiple concentrations of aptamer in plasma with different concentrations of PCSK9 protein.
  
  
  CONCLUSIONS
  The aptamer achieved comparable enrichment to the antibody, but with lower peptide background, thus demonstrating the potential use of aptamers for IA-LC-MS.
authors.affiliation: Translational Biomarkers, Merck Research Laboratories, Rahway, NJ, USA.
authors.forename: Vinita
authors.initials: V
authors.lastname: Gupta
authors.affiliation: Translational Biomarkers, Merck Research Laboratories, Rahway, NJ, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Lassman
authors.affiliation: Translational Biomarkers, Merck Research Laboratories, Rahway, NJ, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: McAvoy
authors.affiliation: Translational Biomarkers, Merck Research Laboratories, Rahway, NJ, USA.
authors.forename: Anita Yh
authors.initials: AY
authors.lastname: Lee
authors.affiliation: Translational Biomarkers, Merck Research Laboratories, Rahway, NJ, USA.
authors.forename: Derek L
authors.initials: DL
authors.lastname: Chappell
authors.affiliation: Translational Biomarkers, Merck Research Laboratories, Rahway, NJ, USA.
authors.forename: Omar F
authors.initials: OF
authors.lastname: Laterza
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry; D000911:Antibodies, Monoclonal / Q000737:chemistry; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D002846:Chromatography, Affinity / Q000379:methods*; D006801:Humans; D059346:Magnets / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D000071449:Proprotein Convertase 9 / Q000032:analysis / Q000097:blood*
chemical_list: D055910:Antibodies, Immobilized; D000911:Antibodies, Monoclonal; D052157:Aptamers, Nucleotide; C472125:PCSK9 protein, human; D000071449:Proprotein Convertase 9
keywords: MS; method development; proteins