SILAC method

Proteomic era opens to new challenges in mass spectrometry, a technique essential for protein identification. Several protocols have been developed in order to improve identification rates. We would like to present you the SILAC method. SILAC means stable isotope labelling amino acid chain, this method is recently used in proteomics for the relative quantification of proteins differentially expressed in two populations of cells.

In this approach essential amino acids are labelled with stable isotopes and added to amino acid deficient cell culture media. Labelled amino acids are incorporated in de novo synthesised proteins that are separated by mass spectrometry. Because the light and heavy amino acid are chemically identical except for their mass difference, the ratio of peak intensities in the mass spectrometer directly yields the ratio of the proteins in two population. The great advantage of SILAC is quantitative rather than qualitative analysis which can be performed. For instance, SILAC could be used to study differentiation process: cellular samples can be harvested at different time point and by comparing with a fixed population, it’s possible to determine protein expression within time period. Furthermore, different stimuli could generate different responses and the expression of different protein patterns. In conclusion, SILAC is really a good and efficient protocol.