Isotope-coded affinity tag

ICAT ( from English- isotope - coded affinity tag, isotope - coded affinity tag ') is a biochemical method for quantitative protein analysis, which is based on a mass spectrometric analysis of a protein based on its mark with a protein tag, which had previously been coupled with different isotopes.

Properties

To the samples to be tested typically consist of three fundamental elements: a functional group which is able to select a specific side chain of an amino acid (e.g., iodoacetamide for labeling of cysteine ​​residues ), isotopes of a surrounded crosslinker and a day (for example. biotin ) for the affinity-based separation of labeled proteins or peptides. In order to quantitatively compare two proteomes, a sample is labeled with the light version of the isotope and the other with the heavy. To minimize errors, digesting the examined substances with protease (usually trypsin) and carry out an avidin affinity chromatography to isolate the jacketed with isotopes peptides. These peptides are then analyzed by LC -MS. The ratio of the signal strengths of the different peptides were labeled with different heavy isotopes, the relative amount of determination used. Originally ICAT has been developed with deuterium, due to interactions with the stationary phase was later converted to 13C.