Peptide synthesis

Peak Peptides

Peak PeptidesCRB specialises in the rapid synthesis of peptides containing stable isotope labelled amino acids.

By using stable-labelled versions of tryptic peptides as internal standards, it is possible to directly quantify protein levels in a digested sample via mass spectrometry.


Critical to the accuracy of this technique is the quality of the stable-labelled peptide. CRB’s custom stable–labelled peptides are offered:

  • Critical to the accuracy of this technique is the quality of the stable-labelled peptide.
  • >95% pure by HPLC
  • analysed for net peptide content.

Post-translational modifications

For the quantitation of post-translational modifications, CRB can also offer stable-labelled peptides containing:

  • phosphoTyr, phosphoSer, phosphoThr
  • sulfoTyr
  • methylated Lys and Arg

Other proteolysis standards

Isotopically labelled versions of peptides derived from proteolysis by other enzymes, such as Lys-C, Glu-C, can also be produced.

The stable-labelled amino acids most commonly used in this technique are shown in Table 1. These amino acids provide the greatest shift in the molecular weight for the least cost; however, heavy atom versions of other amino acids are available upon request.


Streamlined operation allows delivery in 2 – 3 weeks. Most common stable-labelled amino acid building blocks are kept in stock to ensure rapid turn-around.

Technical support

CRB are happy to advise on the design of stable-labelled peptides. CRB can also assist with pre-concentration techniques to significantly reduce the limit of detection via the production of antibody pre-concentration columns.

Upon ordering your peptide, please refer to the peptide buyer’s guide for help on dissolving peptides and their storage. To find out more about peptides see our Technical section.