NIT based analysis. In this service, customers need to provide us a pair of unlabeled protein samples. We’ll carry out tryptic digestion and differentially label the N-terminus of each peptide from the digests with isotopic tags, followed by SCX fractionation, LC-MS based differential analysis, LC-MS/MS based sequencing to identify protein differentials.

SILAC based analysis: In this service, the pair of protein samples will be differentially labeled by our customers by growing one sample in a medium with heavy amino acids (typically Lys and/or Arg), and the other sample in a normal (light) medium. We’ll process the labeled protein samples and carry out digestion, SCX fractionation, LC-MS differential analysis, and LC-MS/MS sequencing to identify protein differentials. In the case where very low abundant proteins are of interest, additional separations at protein level such as SCX or RP-HPLC can be performed.

Reference: details of NIT and SILAC labeling technique can be found in following publications:

Blagoev, B., Kratchmarova, I., Ong, S. E., Nielsen, M., Foster, L. J. and Mann, M,. A proteomics strategy to elucidate functional protein-protein interactions applied to EGF signaling. (2003). Nature Biotechnology. 21, 315-318.

Zhang, X., Jin Q., Carr S.A., and Annan R.S., An N-Terminal Peptide Labelling Strategy For Incorporation Of Isotopic Tags: A Method For The Determination Of Site Specific Absolute Phosphorylation Stoichiometry (2002), Rapid Communication in Mass Spectrometry. 16, 2325-2332.

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