Peptide Synthesis

Synthetic Peptides As Internal Standards

Dr. Catherine Fe nselau 
University of Maryland

  • Synthetic Peptides As Internal Standards
  • Preloaded Resins for Solid-phase Synthesis of Stable Isotope Labeled Tryptic Peptides

Targeted mass spectrometry isotope analysis (i.e. selected reaction monitoring or SRM) is an alternative to antibody-based assays for the validation of clinically relevant biomarkers, but also has been employed for discovery-based quantitative proteomics (see example references below)One obstacle of this strategy is that every peptide possesses unique biochemical characteristics. Its amino acid composition and possible post-translational modifications defines its elution profile from the liquid chromatography column, ionization and fragmentation. For developing a diagnostic clinical MS assay, these peptide properties must be characterized with a synthesized peptide before analyzing the peptide of interest in vivo. Peptides also can be synthesized with heavy stable isotopes for absolute quantitation by spiking in a known amount of the heavy peptide into the biological sample. These strategies are also commonly employed to validate results from large scale quantitative proteomic analyses. 

Frequently Asked Questions 

Does CIL provide custom labeled peptides?

Stable-isotope labeled peptides are used in biomarker discovery and validation as well as in drug and metabolite monitoring, peptide signaling experiments, metabolomics and pharmaco kinetics. CIL is pleased to supply highly enriched and pure amino acids to the world’s leading peptide manufacturers.

Does CIL provide preloaded resins?

Yes, please click here 


Catalog No. Description
L-Arginine (Pbf) (13C6 , 99%; 15N4, 99%) – 2-ClTrt resin
L-Lysine (BOC) (13C6, 99%; 15N2, 99%) – 2-ClTrt resin
L-Arginine (Pbf) (13C6, 99%; 15N4, 99%) – 2-ClTrt resin
L-Lysine (BOC) (13C6, 99%; 15N2, 99%) – 2-ClTrt resin




Percy, A.J.; Hardie, D.B.; Jardim, A.; Elliott, M.H.; Zhang, S.; Mohammed, Y.; Borchers, C.H. 2016. Multiplexed panel of precisely quantified salivary proteins for biomarker assessment. Proteomics, PMID.27538354

Wang, D.; Krilich, J.; Baudys, J.; Barr, J.R.; Kalb, S.R. 2015. Optimization of peptide substrates for botulinum neurotoxin E improves detection sensitivity in the Endopep-MS assay. Anal Biochem, 1;468:15-22 PMID 25232998

Chambers, A.G.; Percy, A.J.; Yang, J. 2013. Multiplexed quantitation of endogenous proteins in dried blood spots by multiple reaction monitoring-mass spectrometry. Mol Cell Proteomics, 12(3):781-91. PMID: 23221968

Hamid, M.; Theo, K.; Bong, K. 2013. Systematic measurement of transcription factor-DNA interactions by targeted mass spectrometry identifies candidate gene regulatory proteins. Proc Natl Acad Sci U S A., PMID: PMC3587231

Karlsson, C.; Malmstrom, L.; Aebersold, R. 2012. Proteome-wide selected reaction monitoring assays for the human pathogen Streptococcus pyogenes. Nat Commun., 18;3: 1301. PMID: PMC3535367

Altvater, M.; Yiming, C.; Melnik, A. 2012. Targeted proteomics reveals compositional dynamics of 60S pre-ribosomes after nuclear export. Mol Syst Biol., 8:628. PMID: PMC3542530

McClatchy, D.B.; Dong, M.Q.; Wu, C.C.; Venable, J.D.; Yates, J.R. III. 2007. 15N metabolic labeling of mammalian tissue with slow protein turnover. J. Proteome Res, 6(5): 2005-10. PMID: 17375949

McClatchy, D.B.; Liao, L.; Park, S.K.; Venable, J.D.; Yates, J.R. 2007. Quantification of the synaptosomal proteome of the rat cerebellum during post-natal development. Genome research, 17(9):1378-88. PMID: 17675365

Venable, J.D.; Wohlschlegel, J.; McClatchy, D.B.; Park, S.K.; Yates, J.R. III. 2007. Relative quantification of stable isotope labeled peptides using a linear ion trap-Orbitrap hybrid mass spectrometer. Analytical chemistry, 79(8):3056-64. PMID: 17367114 

Andrew Percy, PhD

Andrew Percy, PhD

Senior Applications Chemist - Mass Spectrometry

Dr. Andrew Percy is the Senior Applications Chemist for Mass Spectrometry. His responsibilities minimally involve overseeing product development, identifying new product market opportunities, assisting in the analysis of products for MS ‘omics applications, and providing technical support to customers.

Tasha Agreste

Tasha Agreste

Proteomics Product Manager, Deuterated Reagents & Intermediates Product Manager, China Sales - Research Products

Tasha Agreste, Product Manager for the Proteomics product line, has been with CIL since 1989. During her tenure at CIL, Tasha has held various positions including customer service, sales and marketing, where she has proven to be instrumental in enhancing CIL’s customer relationships.