Stable Heavy Isotope Peptide Labeling
Stable Heavy Isotope Peptide Labeling

Heavy Isotope Peptide for Proteomic Quantitation

Absolute quantitation of complex protein mixture at very low concentration requires high quality stable isotope heavy peptide as a standard. The Bio-Synthesis Heavy Stable Isotope Peptide Custom Synthesis Service achieves a success rate well above the industry standard. At Bio-Synthesis, we have produced thousands of custom stable heavy peptides, of scales and purities which meet the ever-increasing need for peptides in the development target assays. These stable isotopic heavy peptides are synthesized using the latest Fmoc solid-phase peptide technology in our state-of-the-art peptide lab. These attributes have enabled us to respond to the ever changing demand for stable isotope labeled compounds. As such, all heavy isotope labeled peptides undergo mass spectrometric analysis and stringent analytical HPLC to establish the final purity, and to assure that our customers receive only the highest quality peptides for absolute quantitation.

At Bio-Synthesis, we strive for excellence through innovation and strict quality control. We conform to Total Quality Management (TQM) as well as ISO-9001 regulations to assure our customers' complete satisfaction.

Custom Stable Isotopic Peptide Labeling Services

Below is a selection of heavy amino acids that can be used for the synthesis of peptides with stable isotopes containing carbon 13 (C13), Nitrogen 15 (N15) and Deuterium (H2).

Amino Acid Code Mass Difference Isotope Isotopic enrichment
Alanine A +4Da U- 13C3, 15N >99%
Arginine   R +10Da U- 13C6, 15N >99%
Isoleucine I +7Da U- 13C6, 15N >99%
Leucine  L +8Da U- 13C6, 15N >99%
Lysine K +8Da U- 13C6, 15N >99%
Phenylalanine F +10Da U- 13C9, 15N >99%
Proline P +6Da U- 13C5, 15N >99%
Valine V +6Da U- 13C5, 15N >99%
Contact us for other amino acids not listed above

Service Provided:

We provide a lyophilized peptide of the specified sequence, purity, and quantity along with the associated QC reports. Our turnaround is typically 10-15 days. Every step of the peptide synthesis process is subject to stringent quality control using MALDI MS and analytical HPLC.


Biological systems are typically investigated in order to identify all the components of the system and to monitor the quantitative changes that may occur during different metabolic phases, such as the different stages in the cell cycle. Significant progress has been made in recent years in biological research, allowing scientist to covalently modify peptides via sulfonation or guanidination to permit de novo sequence determination by MS/MS analysis. Furthermore, multiple strategies have been developed in the fields of qualitative and quantitative proteomics that employ 1D and 2D-gel electrophoresis, affinity tag reagents, and stable-isotope labeling. For example, the use of the absolute quantification method (AQUA) allows targeted quantification of protein and post-translational modifications in complex protein mixtures. The method employs stable isotope-labeled peptides as internal standards (SIS peptides). Stable isotopes are non-radioactive chemical isotopes that do not decay spontaneously.

Important stable isotopes used for the study of biological systems include those of oxygen (18), carbon (13), nitrogen (15), hydrogen (2) and sulfur (32). Internal peptide standards can be used to study different biological states, such as differences in expressed proteins found in pathophysiological cells compared to normal cells. Since peptides containing stable isotopes are often biologically active, they can be used for structure-function studies as well. Furthermore, incorporation of isotopes that have a nonzero spin such as 2H (spin 1), 13C (spin 1/2), and 15N (spin 1/2) into selected positions of amino acids or peptides by chemical or enzymatic means allows the use of these peptides for NMR studies and to help determine their solution structure.

  • Proteomic quantitation
  • Quantitate post-translational modified protein
  • Verification of outcomes derive from RNAi
  • Pharmacokinetics and Metabolomics analysis
  • Protein expression tracking
  • Cell signal profiling as well as pathway recognition
  • Biomarker discovery

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Literature available for download:

Stable Isotope-Labeling