Isotope Labeled Peptides
Isotope labeled peptides are ideal internal standards and template analytes.
Isotope labeled peptides contain isotope labeled amino acids with atom substitution of respective heavy isotopes. The most frequent substitutions of non-radioactive amino acids are 12C by 13C, 14N by 15N, 1H by 2H (deuterium).
Stable isotope labeled peptides (SIL peptides) chemically and physically indistinguishable from endogenous counterparts in retention time, ionization efficiency, and fragmentation pathways. Therefore, all peptides are ideal internal standards and template analytes. Normally, peptides can be labeled with one or more isotopes of hydrogen, carbon, nitrogen, or oxygen by incorporation of amino acids with desired isotopes in synthesis, like: deuterium (D), C13, N15, O18.
Isotopic Labeling Chemistry
QYAOBIO provides customized peptides with stable isotopes labeling, including 2H (deuterium), 15N (nitrogen-15), 13C (carbon-13), or 15N/13C combination. Stable isotope labeled peptides are applied widely in the nuclear magnetic resonance (NMR) spectroscopy and mass spectroscopy (MS), the SIL peptides are the reference materials for pharmacokinetic analysis and metabolite identification. Furthermore, 13C and 15N labeling peptides are suitable for NMR research of protein structure, dynamics, and molecular interactions. Other application of SIL peptides are protein structure analysis, protein expression monitoring, protein cross-linking analysis, quantitative proteomics, biomarker discovery, cell signal profiling, and pathway validation.
15N and 13C are the two major isotopes, which are incorporated into a specific amino acid sequence of peptides. Each atom contains over 99% of an enriched isotope, its location is at multiple positions within the peptides. The following table is the stable isotopic amino acid containing Carbon 13 and Nitrogen 15. For specific Deuterium (H2) peptide labeling, please contact us for professional suggestion.
Our stable isotope labeled peptide are synthesized by applying highly enriched isotopic amino acids for the Fmoc-based solid-phase peptide synthesis. All isotopic amino acids have >99% purity, this enables us to synthesize the stable isotopic peptides with the best quality. All labeled peptides undergo mass spectrometic analysis and stringent analytical HPLC to ensure the high purity.
SIL Peptide Specifications
- 2H, 13C, 15N, 18O isotope-labeled peptides
- Purity: >95%
- Net weight determination
- Min order quantity: 1mg gross weight
- Labeling one or more amino acid positions.
- Lyophilized peptides shipping
Stable Isotope Labeled Peptides
Peptides labeled with stable and non-radioactive isotopes are efficient for convenient detection in research. Stable isotope labeled amino acids, also known heavy isotope, are derived from natural amino acids by certain atom’s substitution with the heavy isotope variant. The most common substitutions are 12C by 13C (carbon-13), 14N by 15N (nitrogen 15), and 1H by 2H (deuterium).
Isotope Labeled Amino Acids
Stale isotope labeled peptides (heavy isotope labeled peptide) display identical physio-chemical properties and chemical reactivity as non-labeled counterparts, apart from some exceptions. However, the minute mass difference make labeled, and unlabeled peptides behave differently under certain conditions. This constitutes the basis for Absolute QUAntitation (AQUA) applications, such as quantitative proteomics, NMR studies.
| Amino Acid | Letter Code | Isotope | Mass difference | Isotopic Enrichment |
| Alanine | Ala, A | 13C3, 15N | +4 Da | >99% |
| Arginine | Arg, R | 13C6, 15N4 | +10 Da | >99% |
| Isoleucine | Ile, I | 13C6, 15N | +7 Da | >99% |
| Leucine | Leu, L | 13C6, 15N | +7 Da | >99% |
| Lysine | Lys, K | 13C6, 15N2 | +8 Da | >99% |
| Phenylalanine | Phe, F | 13C9, 15N | +10 Da | >99% |
| Proline | Pro, P | 13C5, 15N | +6 Da | >99% |
| Valine | Val, V | 13C5, 15N | +6 Da | >99% |
The Absolute Quantification method (AQUA) applies SIL peptides as internal standards to target quantification of proteins and post-translational modifications in complex protein mixtures. The stable isotope-labeled peptides are introduced into biological samples during or after protease digestion, then the heavy SIL peptide and its light endogenous peptide fragment are detected by selected reaction monitoring (SRM) in the mass spectrometer(MS). The amount of endogenous protein is calculated on the base of the known amount of SIL peptide addition and the intensity ratio of both peptides.
SIL Peptide Applications
Proteomics are the study of proteins encoded by the genome, includes the identification of post-translational modifications, structural analysis, protein localization studies, and protein quantitation. Stable isotope labeled peptides have the same properties as endogenous counterparts in retention time, ionization efficiency and fragmentation mechanism. However, the only mass difference makes labeled, and unlabeled peptides behave differently. This makes SIL peptides are applied widely in:
- Quantification analysis of ICAT, iTRAQ, AQUA.
- Nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS).
- Reference materials for pharmacokinetic analyses and metabolite identification.
In addition, Stable isotopic labeled peptide have widely applications in proteomics, the specific research areas including:
- Functional quantitative proteomics
- Quantitation of post translation-modified proteins
- Protein structure analysis
- Protein expression monitoring
- Protein cross-linking analysis
- Protein production monitoring
- Biomarker discovery
- Pharmacokinetics
- Metabolomics
- Clinical biochemistry of drug and metabolite monitoring
- Anti-doping testing
- Cell signal profiling and pathway validation
- Allergen quantitation
Custom Isotope Labeled Peptide Synthesis
QYAOBIO provide custom isotope labeled (SIL) peptide synthesis for customers in worldwide.
SIL Peptide Modifications
SIL peptides can be medicated with different methods to satisfy various customer requirements. The common modification methods of stable isotope labeled peptides are:
- Phospho-Tyr, Ser, Thr (single or multiple)
- Sulfo-Tyr (single or multiple)
- Methylated Arg, Lys
- Chloro-Tyr
- Met-oxidized
- Pyroglutamic acid
High Quality SIL Peptide Service
QYAOBIO is a reliable partner in SIL peptides synthesis, we can assist you to accelerate in research and study process. Our professional service features including:
- SIL peptides with excepted design and mass difference
- Easy and efficient quantification by MS assay
- Free radioactive hazard
- Various assorted modifications like disulfide bond formation
- Strict QC testing for mass and purity
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