Element-coded affinity tag

Lee, S., Young, N.L., Whetstone, P.A., Cheal, S.M., Benner, W.H., Lebrilla, C.B., and Meares, C.F. (2006) A method to site-specifically identify and quantitate carbonyl end products of protein oxidation using oxidation-dependent element coded affinity tags (O-ECAT) and nanoLiquid chromatography Fourier transform mass spectrometry./. Proteome Res. 5(3), 539-547. 

Meares, C.F., Whetstone, P.A., Corneillie, T.M., Butlin, N.G. (2007) Element-coded affinity tags. US... 

Gant-Branum, R. L. Kerr, T. J. McLean, J. A., Relative quantitation of phosphory-lated peptides and proteions using phosphopeptide element-coded affinity tagging (PhECAT) , Analytical Chemistry 2010, in preparation. 

Sulfur exists in cysteine and methionine and is one of the most abundant elements in natural proteins. The cumulative abundance of sulfur in proteins is about 5%. The relative amount of proteins can be obtained by the isotopelabeling method with the sulfhydryl group and molecular mass spectrometry measurement, such as the isotope-coded affinity tags (ICAT) method. On the other hand, when the amino acid sequence of a protein has been identified, the absolute amount of a protein can be obtained via the determination of sulfur with ICP-MS. In comparison with other naturally existing elements in proteins, sulfur is preferable as an internal standard for protein quantification due to its high abundance. ... 

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