Chemical Labelling

Isotopically labelled standards for proteomic measurements can be prepared using chemical or biological labelling strategies. Stable isotope labelling may be performed at either the peptide level (via solid-phase peptide synthesis) or the protein level (via recombinant gene expression).

To support the synthesis of stable isotope-labelled peptides, Cambridge Isotope Laboratories Inc. (CIL) offers a comprehensive range of:

• Protected isotope-labelled amino acids

• Preloaded resins

• Labelling reagents for solid-phase synthesis

For the expression of stable isotope-labelled proteins, CIL supplies:

• Isotope-enriched cell culture media

• Cell-free protein expression reagents and kits (including products from CellFree Sciences)

In addition, CIL offers select full-length labelled proteins (e.g. CRP, ubiquitin) for use in bottom-up LC-MS workflows.

Each synthesis or expression product is described and referenced on its associated product page. Follow the links below for more detailed information on specific product areas.

Targeted mass spectrometry analysis — including selected reaction monitoring (SRM) and multiple reaction monitoring (MRM) — provides a powerful alternative to antibody-based assays for the validation of clinically relevant biomarkers. These approaches are widely used in both clinical proteomics and discovery-based proteomic research, offering high specificity, sensitivity and reproducibility when combined with stable isotope-labelled peptide standards.

Stable isotope-labelled cellular biomass can be used in both proteomic and metabolomic investigations. Quantitative LC-MS proteomic studies benefit significantly from the use of purified, labelled intact proteins as internal standards, improving accuracy, reproducibility and confidence in quantitation across complex biological samples.