Peptide Modifications
Isotope Labeled Peptides
What is Isotope Labeled Peptides?
Stable isotope labelling is a chemical reagent in which the molecules of a compound contain one or more stable isotope atoms and are analysed and determined using their unique tracer properties.
Stable isotope labelling techniques are based on the principle of labelling a reactant by replacing specific atoms with an isotope, which then causes the reactant to undergo a reaction and detects the atoms with a change in neutron number, which can be tracked by reactions, metabolic pathways or cells. Stable isotope (13C, 15N, 13C15N) labelled peptides are commonly used as ‘chemical tags’ in quantitative proteomics for the detection and tracing of biological samples. Quantitative proteomics methods mainly use high-resolution mass spectrometry to separate isotope-labelled and non-labelled peptide ions or peptide ions, and use the intensity values of their detected signals for quantitative calculations.
Stable isotope labelling technology has the advantages of high sensitivity, simple positioning and accurate quantification, which makes isotope modification get more and more widespread attention in the field of medicine and biochemistry.

Isotope Labeled Peptides
Precision Tools for Research
Stable isotope labeled peptides are synthesized by substituting specific atoms in natural amino acids with heavy isotopes, such as replacing 12C with 13C, 14N with 15N, or 1H with 2H (deuterium). These modifications result in isotope labeled compounds that retain the same physiochemical properties and chemical reactivity as their non-labeled counterparts. This makes them indispensable in a wide array of scientific applications, including mass spectrometry, NMR studies, and pharmacokinetic analyses.
Amino Acid |
Isotope |
Mass Difference to non-labeled AA |
---|---|---|
Alanine |
U- 13C3, U-15N |
+4 Da |
Arginine |
U- 13C6, U-15N4 |
+10 Da |
Leucine |
U- 13C6, U-15N |
+7 Da |
Lysine |
U- 13C6, U-15N2 |
+8 Da |
Phenylalanine |
U- 13C9, U-15N |
+10 Da |
Proline |
U- 13C5, U-15N |
+6 Da |
Valine |
U- 13C5, U-15N |
+6 Da |
Featured Citations
Using stable isotope labeling to advance our understanding of Alzheimer’s disease etiology and pathology
Stable isotope labeling with mass spectrometry (MS)-based proteomic analysis has become a powerful strategy to assess protein steady-state levels, protein turnover, and protein localization. Applying these analyses platforms to neurodegenerative disorders may uncover new aspects of the etiology of these devastating diseases. Recently, stable isotopes-MS has been used to investigate early pathological mechanisms of Alzheimer’s disease (AD) with mouse models of AD-like pathology. In this review, we summarize these stable isotope-MS experimental designs and the recent application in the context of AD pathology. We also describe our current efforts aimed at using nuclear magnetic resonance (NMR) analysis of stable isotope labeled amyloid fibrils from AD mouse model brains. Collectively, these methodologies offer new opportunities to study proteome changes in AD and other neurodegenerative diseases by elucidating mechanisms to target for treatment and prevention.
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