The protein Absolute QUAntification (AQUA) is a targeted proteomics strategy that enables robust protein quantification at very low concentration in complex protein mixtures.
AQUA relies on the synthesis of stable isotope labeled native peptides of a protein of interest and their use as internal standards during the LC-MS/MS analysis. Labeled tryptic peptides incorporate heavy amino acids (typically 13C and 15N enriched Lysine or Arginine) that create a slight molecular weight difference with the original peptides without modifying their chemical properties. AQUA peptides can be prepared with covalent modifications such as phosphorylation, methylation or acetylation. The addition of a controlled amount of labeled peptide in the protein sample before digestion and Selected Reaction Monitoring (SRM) analysis enables a precise determination of the quantity of native peptide in the sample.
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AQUA workflow
Peptides used in the protein AQUA approach can be prepared using solid phase peptide synthesis or cellular biology.
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Cortec Isotope offers a selection of protected labeled amino acids for peptide synthesis, allowing straightforward incorporation of 13C, 15N labeled amino acids to the peptide chain.
For flexible incorporation of heavy isotopes, non-natural amino acids and specific tags into the peptides, trust our expertise with cell-free expression. Our cell-free expression kits employ cellular extracts that exploits the transcription and translation mechanisms of E. coli to produce peptides or proteins in a defined chemical environment.
Cortec Isotope proposes to help you label your protein. For inquiry, please contact our labeled protein expression platform.