Unlock more insights from your proteomics experiments with high-quality, cost-effective, and custom-made isotope-labeled peptides. Our advanced peptide synthesis and modification platform allows you to choose from a range of stable labels with high isotopic purity and synthesize peptides with up to 150 amino acids. Contact us today to learn more.

When to use isotope-labeled peptides in your project

Stable isotope-labeled peptides are invaluable reagents for protein quantitation, detection, and structural characterization studies. These reagents are chemically synthesized through the cost-effective Fmoc solid-phase method employing uniformly labeled amino acids with a high degree of isotopic purity (>99%). The most used stable amino acids include deuterium (2H), carbon-13 (13C), and nitrogen-15 (15N), which can be incorporated individually or in combination.

Heavy isotopes like 13C add mass to a peptide while preserving its reactivity, and chemical and physical properties. Researchers can then leverage this shift to perform high-precision measurements through mass spectrometry, NMR, and other advanced methods.

The versatility of isotope-labeled peptides makes them a valuable tool for a wide range of protein research applications. If you are considering using isotope-labeled peptides in your project, our team of experts can help you choose the right labels and design a custom synthesis strategy to meet your specific needs. Contact us today to learn more:

Common applications of isotope-labeled peptides

Isotope-labeled peptides are widely used in a variety of research and industry applications, including:

  • Proteomics and metabolomics studies: these studies assess the structure, function, interactions, and fate of proteins within a system or organism. Isotope-labeled peptides can be used as internal standards for precise quantification, allowing the accurate measurement of protein expression levels in health and disease.
  • Quality control of large-scale protein production: these modified peptides can be used to monitor the purity and integrity of proteins during production, ensuring that the final product meets quality standards.
  • Drug metabolism and bioavailability studies: clinician researchers can employ these high-purity reagents as internal standards. This allows them to monitor the fate of a drug in the body and understand how it is metabolized and excreted.
  • Biomarker quantification for diagnostic applications: these peptides can be used to detect or quantify biomarkers, to determine the severity or type of a particular disease and, thus, help medical practitioners select the best treatment plan.

In all these applications, isotope-labeled peptides are typically spiked into samples in known concentrations and analyzed using advanced spectrometry techniques, enabling precise quantitative measurements. If you are interested in using isotope-labeled peptides for your project, our team of experts can help you choose the right labels and design a custom synthesis strategy to meet your needs.

Mass Spectrometry

Mass Spectrometry is emerging as the reference method for absolute protein quantitation: a sample tryptic digest is spiked with one of the chemically synthesized “tryptic” peptides containing one or more heavy isotope labeled amino acids. The observed signals between the endogenous tryptic peptide and slightly heavier synthetic tryptic peptide, are then compared. It is strongly recommended to quantify the net content of the chemically synthesized “tryptic” peptide with our quant-peptide service or using standard CHN analysis.

Stable isotope labeled peptides demonstrate identical chemical and physical properties. They behave in the same manner as non-labeled peptides, they only differ by mass.
Thanks to this delta mass, SIL peptides are useful in quantitative proteomics for relative protein quantification. Such as ICAT (Isotope Coded Affnity Tags) and iTRAQ (isobaric Tags for Relative and Absolute Quantifcation). SIL are also useful for absolute protein quantification applications MRM (Multiple Reaction Monitoring) and AQUA (Absolute QUAntification of proteins). And NMR studies and mass spectrometry techniques based on their well-defined increase in molecular weight compared to the native peptide.

Nuclear magnetic resonance (NMR) spectroscopy

NMR spectroscopy is a key tool in structural biology research, allowing for the characterization of protein structures, protein dynamics, and protein-protein interactions. It is advantageous over X-ray crystallography, in that the structures of proteins or peptides in liquid can be solved. Additionally, recent advances in NMR spectroscopy have demonstrated its value in drug discovery, due to its ability to help researchers directly identify ligand binding sites.

The technique involves subjecting a sample to a magnetic field, taking advantage of an intrinsic property of certain atomic nuclei, called spin. In response to the magnetic field, nuclear spins flip from low energy spin states to higher energy states. As the spins flip, energy is absorbed by the nucleus. Absorption spectra data can be used to identify atomic nuclei and the distance between nuclei.

Stable isotopic labeling of peptides allows for the incorporation of NMR active nuclei which can help reduce the complexity of spectra and help scientists obtain new correlations between atoms, for more complete structural information.

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