LifeTein can provide customized peptides labeled with stable isotopes, including 2H (deuterium), 15N (nitrogen-15), 13C (carbon-13), or a combination of 15N/13C. Stable isotope labeled peptides and deuterated peptides have been widely applied in the nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) and reference materials for pharmacokinetic analyses and metabolite identification. Peptides labeled with 13C and 15N are suitable for NMR studies of protein structures, dynamics, and molecular interactions of biomolecules. Other applications include the protein structure analysis, protein expression monitoring, protein cross-linking analysis, quantitative proteomics, biomarker discovery, cell signal profiling, and pathway validation.
In a deuterated peptides, some of the hydrogen atoms within the molecular structure have been substituted with deuterium, a heavier and stable isotope of hydrogen. Due to the kinetic isotope effect, peptide drugs containing deuterium may exhibit notably slower metabolic rates, resulting in an extended half-life. During deuteration, each amino acid constituting a peptide can undergo deuteration, or specific amino acids can be targeted for deuteration. For instance, if a peptide contains five Leucine residues, all Leucine residues within the peptide can be deuterated.
Below is a selection of stable isotopes containing carbon 13 (C13) and Nitrogen 15 (N15). Please contact us for the Deuterium (H2) peptide labeling.
| 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% |
LifeTein's stable isotope labeled peptides are synthesized using the highly enriched stable amino acids for the Fmoc-based solid-phase custom peptide synthesis at our laboratory in New Jersey. All the labeled amino acids have > 99% isotopic purity. The high purity Fmoc materials have enabled us to synthesize the best quality stable isotope peptides successfully. All labeled peptides undergo mass spectrometric analysis and stringent analytical HPLC to ensure the final high purity. The isotopes of 15N and 13C are incorporated into the unique amino acid sequence of peptides. For example, an Arginine (13C6,15N4) has four 15N and six 13C. A peptide containing one isotope-labeled Arginine would be +10 Da more than its unlabeled counterpart.
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