Custom Protein Expression

Full length SIL proteins

For quantitative mass spectrometry projects focusing on one or only a few proteins, purified stable isotope-labelled (SIL) proteins are the gold standard. The biochemical properties of the SIL proteins are similar to those of the respective target protein, making the SIL protein ideally suited for absolute protein quantification using liquid chromatography-mass spectrometry (LC-MS). The SIL proteins can be added at early time points during sample preparation, providing highly accurate quantification results. If you are planning to quantify several tens of proteins in parallel, our custom-made QconCAT proteins are the most suitable reference standards.

What we offer:

  • Production of recombinant full length proteins in E. coli for application as reference standard in targeted mass spectrometry.
  • Isotopic labelling of your choice or unlabelled proteins.
  • Different grades of purity (crude extract, IMAC purified, high purity).
  • Choose a protein from the continuously expanding list below or contact us to receive an individual quote for your custom protein production.
  • Quality control with LC-MS/MS (labelling, purity).


Our highly skilled professionals have years of experience producing recombinant proteins in E. coli at various scales. Our service includes protein production from gene to protein, starting with small scale expression (ng to µg scale) up to production of several grams of protein (large scale). The production of reference standards for mass spectrometry requires correct sequence and length of the proteins, but not correct folding and/or activity. Thus, unless stated otherwise for certain proteins, the purified proteins will be not checked for correct three-dimensional folding and/or activity.

Available SIL proteins:

Protein Organism Uniprot ID Gene name Amount Label* Price (€)  
p53, isoform 4 Human P04637-4 P53_HUMAN 100 µg 15N 300.00
eGFP Derived from Aequorea Victoria 100 µg 15N 300.00
Keratin, isoform 16 Human P08779 KRT16A 100 µg 15N 300.00

* other types of labelling are available upon request

Not found what you are looking for? Contact us directly for designing your custom protein expression project.

Our prices are net prices, i.e. they do not contain value added taxes or customs fees. These taxes have to be paid by the customer.
The ordered products are usually shipped 1-2 business days after receiving the order.

Delivery costs depend on destination and packaging (either on dry ice or ambient temperature shipping).

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