Thermo Scientific Heavy and Light Amino Acids are used to specifically analyze protein expression by mass spectrometry using stable isotope labeling with amino acids in cell culture (SILAC) quantification kits. This is a lyophilized preparation of L-Leucine, sufficient for 10 SILAC experiments.

General features of heavy and light amino acids for SILAC labeling:

• Efficient—100% label incorporation into proteins of living cells
• Flexible—different isotopes of heavy and/or light amino acids for arginine, lysine, leucine and proline enable the quantitation of peptides derived from MS-grade proteases
• Multiplex capabilities—several alternative isotopes of arginine and lysine are available that allow the analysis of multiple treatment conditions in each experiment
• High-quality supplements—heavy amino acids with >99% isotope purity

Stable isotope labeling with amino acids in cell culture (SILAC) is a powerful method to identify and quantify relative differential changes in complex protein samples. This approach entails the in vivo metabolic incorporation of 'heavy' ¹³C- or ¹⁵N-labeled amino acids into proteins followed by mass spectrometry (MS) for the accelerated and comprehensive identification, characterization and quantitation of proteins.

Thermo Scientific Heavy and Light Amino Acids for SILAC are used together with specialized cell culture media that are deficient in essential amino acids. Heavy and light L-lysine and L-arginine are the most common amino acids used for SILAC analysis of tryptic peptides. Up to three different experimental conditions can be readily analyzed with different isotopes of lysine and arginine. For lysine three-plex experiments, 4,4,5,5-D₄ L-lysine and ¹³C₆ ¹⁵N₂ L-lysine are used to generate peptides with 4- and 8-Da mass shifts, respectively, compared to peptides generated with light lysine. For arginine three-plex experiments, ¹³C₆ L-arginine and ¹³C₆ ¹⁵N₄ L-arginine are used to generate peptides with 6- and 10-Da mass shifts, respectively, compared to peptides generated with light arginine. L-leucine is another amino acid commonly used for SILAC labeling, because it is one of the most common amino acids found in protein sequences. Proline is a non-essential amino acid that is sometimes added to SILAC media to prevent the metabolic conversion of heavy arginine to heavy proline in mammalian cell lines with high arginine dehydrogenase activity.

Related Products
L-Arginine-HCl for SILAC
L-Proline for SILAC
L-Lysine-2HCl for SILAC