TAG-MASS

Gu, S Du, Y Chen, J., Liu, Z Bradbury, E.M., Hu, C.A., Chen, X. (2004). Large-scale quantitative proteomic study of PUMA-induced apoptosis using two-dimensional liquid chromatography—mass spectrometry coupled with amino acid-coded mass tagging. J. Proteome Res. 3, 1191 1200. 

A different MS-based ee-assay makes use of a proline-derived mass-tagged acylating agent.95 In the course of derivatization it is necessary that some degree of kinetic resolution comes about. The sensitivity of the method was reported to be 10% ee. It can also be applied to the reaction of a prochiral compound lacking enantiotopic groups, as in the transformation of acetophenone to phenylethanol. 

The following sections describe some of the major mass tag types and discuss the general protocols for their use. 

Figure 16.6 The solid phase ICAT reagent provides a thiol-reactive iodoacetyl group to capture cysteine peptides, a spacer containing stable isotopic labels, and a photo-cleavable group that can release the captured peptides for mass spec analysis. The VICAT mass tag is a solution phase labeling agent that also has a photo-cleavable site to release isolated peptides from a (strept)avidin affinity resin. This compound adds a fluorescent group to better detect labeled peptides as they are being isolated from a sample.

Figure 16.7 The ECAT mass tag consists of a DOTA metal chelate group that can coordinate a lanthanide metal ion and a bromoacetyl group for coupling to cysteine-containing proteins.

ECAT mass tag linked to protein via thioether bond... 

The use of mass tagging reagents to analyze proteomic data has greatly improved the ability to compare samples for protein expression differences. However, a major limitation of the ICAT procedure (Section 1, this chapter) is that it can only compare two samples simultaneously, usually a test and a control. Even with the ECAT design (Section 2) using multiple lanthanide metals to make a series of different mass tag signatures, it is difficult to extend the... 

Figure 16.10 The O-ECAT mass tag can covalently link to any oxidized proteins containing aldehydes, forming an oxime bond.

Thompson, A., Schafer, J., Kuhn, K., Kienle, S., Schwarz, J., Schmidt, G., Neumann, T., and Hamon, C. (2003) Tandem mass tags A novel quantification strategy for comparative analysis of complex protein mixtures by MS/MS. Anal. Chern. 75(8), 1895-1904. 

Thompson, A., Prescott, M., Chelebi, N., Smith, J., Brown, T., and Schmidt, G. (2007) Electrospray ionisation-cleavable tandem nucleic acid mass tag-peptide nucleic acid conjugates Synthesis and applications to quantitative genomic analysis using electrospray ionisation-MS/MS. Nucleic Acids Res. 35(4), e28. 

CONRADS, T.P., ANDERSON, G.A., VEENSTRA, T.D., PASA-TOLIC, L., SMITH, R.D., Utility of accurate mass tags for proteome-wide protein identification, Anal. Chem., 2000, 72, 3349-3354. 

Smith R.D., Anderson G.A., Lipton M.S., Masselon C., Pasa-Tolic L., Shen Y., and Udseth H.R. (2002), The use of accurate mass tags for high-throughput microbial proteomics, Omics 6, 61-90. 

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