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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. 


Stable Isotope-Labeled Peptide and Protein Reagents and Kits


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 pharmacokinetics. CIL is pleased to supply highly enriched and pure amino acids to the world’s leading peptide manufacturers.

Would 0.8 mM of Lysine or Arginine preloaded resins provide approximately 8 synthesis at 0.1 mM scale?

Yes, theoretically 0.8 mM of resin would provide 8 synthesis at 0.1MM scale. Final yields are always dependent on actual sequence and the efficiency of the couplings.

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




Lau, J.K.-C.; Lam, K.H.B.; Lai, C.-K.; et al. 2019. Imidazolone formation from pronated tetrapeptides: effects of replacing a glycine by an alanine or proline residue. Int J Mass Spec, 435, 69-77. ScienceDirect:

Li, F.; Cui, L.; Yu, D.; et al. 2019. Exogenous glutathione improves intracellular glutathione synthesis via the γ-glutamyl cycle in bovine zygotes and cleavage embryos. J Cell Physiol, 234(5), 7384-7394. PMID: 30362550

Orti, V.; Mertens, B.; Vialaret, J.; et al. 2018. Data from a targeted proteomics approach to discover biomarkers in saliva for the clinical diagnosis of perioddontitis. Data Brief, 18, 294-299. PMID: 29900194

Peng, X.; Xu, X.; Wang, Y.; et al. 2018. A-to-I RNA editing contributes to proteomic diversity in cancer. Cancer Cell, 33(5), 817-828. PMID: 29706454

LeBlanc, A.; Michaud, S.A.; Percy, A.J.; et al. 2017. Multiplexed MRM-based protein quantitation using two different stable isotope-labeled peptide isotopologues for calibration. J Proteome Res, 16(7), 2527-2536. PMID: 28516774

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, 17(6). PMID: 27538354

Delgado, D.A., Doherty, K.; Cheng, Q.; Kim, H.; Xu, D.; Dong, H.; Grewer, C.; Qiang, W. 2016. Distinct Membrane Disruption Pathways Are Induced by 40-Residue β-Amyloid Peptides. J Biol Chem, 29(23), 12233-12244. PMID: 27056326

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, 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, 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), 2005-2010. 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 Res, 17(9), 1378-1388. 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. Anal Chem, 79(8), 3056-3064. PMID: 17367114 

Kevin Millis, PhD

Kevin Millis, PhD

Senior Scientist, Application Development Manager

Kevin Millis, PhD, is the Senior Scientist and Market Development Manager for all NMR and Mass Spectrometry product lines. Kevin is responsible for Technical Services both internally and externally for all CIL customers as well as being responsible for the application and market development for the CIL products.