Isotope Tags

Generally, methylation of enolate ions with isotopically tagged methyl iodide is a satisfactory labeling procedure. For example, application of this method has given the C-18 labeled steroids, (244) and (245) (see above), 17 -acetoxy-4jS-trideuteriomethyl-4a-methyl-l9-norandrost-5-en-3-one (264) and 19- C-testosterone acetate (268). Methylation of the anion derived from 17jS-acetoxy-4-methyl-l9-norandrost-4-en-3-one (263) with d3-methyl iodide occurs predominantly at C-4, yielding mainly the 4)S-trideuterio-methyl derivative (264) and about 10% of the corresponding C-4 epimer... 

Tao WA, Aebersold R (2003) Advances in quantitative proteomics via stable isotope tagging and mass spectrometry. Curr Opin Biotechnol 14 110-118... 

Mullet D.R. et al. (2001) Isotope-tagged cross-linking reagents. A new tool in mass spectrometric protein interaction analysis. Anal. Chem. 73, 1927-1934. 

Zappacosta, F., and Annan, R.S. (2004) N-terminal isotope tagging strategy for quantitative proteomics Results-driven analysis of protein abundance changes. Anal. Chem. 76, 6618-6627. 

Zhou, H., Ranish, J.A., Watts, J.D., and Aebersold, R. (2002) Quantitative proteome analysis by solid-phase isotope tagging and mass spectrometry. Nat. Biotechnol. 20, 512-515. 

Fig. 8. An overview of the zero order energy levels of the doubly isotopically tagged helix. The isotope shifts are Sa (13C=I80) and Sb (l3C=l80) while Aa and Ab are diagonal anharmonicities. The shaded areas represent the helix one- and two-exciton bands that become perturbed by the isotopes. The solid (bra evolution) and dashed (ket evolution) arrows represent one of the Liouville paths contributing to the echo.

Labelling the 3-APTHS molecule with "OH groups provides an isotopic tag at the site on the molecule where cross-linking should take place. 3-APTHS hydrolyzed in 97.8 at %, 80 labelled water was spun onto sample substrates in the manner described above and SSIMS spectra were acquired both at room temperature and after heating of the sample to 100°C in vacuum for 1 h. The relative intensity of the oxygen containing ions produced by these samples can be... 

M. Li and J. A. Kinzer, Structural analysis of oligosaccharides by a combination of electrospray mass spectrometry and bromine isotope tagging of reducing-end sugars with 2-amino-5-bromopyridine, Rapid Commun. Mass Spectrom., 17 (2003) 1462-1466. 

Nucleotide tags Peptide tags Haloaromatic tags Secondary amine tags Isotopic tags Autotagging... 

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