Stable isotope identification

Morris SA, S Radajewski, TW Willison, JC Murrell (2002) Identification of the functionally active methano-troph population in a peat soil microcosm by stable-isotope probing. Appl Environ Microbiol 68 1446-1453. 

Radajewski S, G Webster, DS Reay, SA Morris, P Ineson, DB Nedwell, 11 Prosser, JC Murrell (2002) Identification of active methylotroph populations in an acidic forest soil by stable-isotope probing. Microbiology (UK) 148 2331-2341. 

In essence, NAA involves converting some atoms of the elements within a sample into artificial radioactive isotopes by irradiation with neutrons. The radioactive isotopes so formed then decay to form stable isotopes at a rate which depends on their half-life. Measurement of the decay allows the identification of the nature and concentration of the original elements in the sample. If analysis is to be quantitative, a series of standard specimens which resemble the composition of the archaeological artifact as closely as possible are required. NAA differs from other spectroscopic methods considered in earlier chapters because it involves reorganization of the nucleus, and subsequent changes between energy levels within the nucleus, rather than between the electronic energy levels. 

Commonly used isotope labels in metaboHc flux analysis and pathway identification are H, and The most prominent stable isotope is The... 

Diagnosis of medium chain acyl-CoA dehydrogenase deficiency by stable isotope dilution analysis of urinary acylglycines retrospective and prospective studies, and comparison of its accuracy to acylcamitine identification by FAB/mass spectrometry. 

Deuterium or "Heavy Hydrogen". D2 gas, mw 4.03 fr p 13-95°K, bp 20.57°K, d of liq 169 g/liter was first isolated in concns sufficient for positive identification by Urey et al at Columbia Univ in 1931. Deuterium is a stable isotope and occurs in natural hydrogen, water and other H-bearing compds in an av abundance of 0.015 mole %. It is of interest to research workers as a tracer in biological processes in chem reactions. There is now commercial production of Deuterium St Heavy Water (Ref 2). It... 

Lesage, D., Virelizier, H., Jankowski, C.K., Tabet, J.C. 1998. Identification of isomeric tributylphosphate dimers formed by radiolysis using tandem mass spectrometry and stable isotopic labelling. Eur. Mass Spectrom. 4 47-54. 

They generally lack sensitivity and a direct relation to molecular structure. GC-MS is fast, direct, and very sensitive, and the spectrum provides a result which puts identification beyond dispute. Computer-assisted systems are now available which embody extensive drug reference libraries and can be automatically searched to identify unknown spectra. The further development of chemical ionization and mass fragmentography methods using stable isotopes now permits very accurate quantitative work. 

Stribling, J.M., and Cornwell, J.C. (1997) Identification of important primary producers in a Chesapeake Bay tidal creek system using stable isotopes of carbon and sulfur. Estuaries 20, 77-85. 

Identification of recharge areas of the Maximum Springs, applying stable isotopes, tritium, carbon-14, and helium... 

Browne TR, Szabo GK, Ajami A, Wagner D (1993). Performance of human mass balance/metabolite identification studies using stable isotope (13C, 15N) labeling and continuous-flow isotope-ratio mass spectrometry as an alternative to radioactive labeling methods. J Clin Pharmacol 33 246-252... 

Figure 4.10. Proteomic analysis by SILAC. Proteomic analysis by SILAC or stable isotope labeling of amino acids in cell culture utilize de novo metabolic incorporation of stable-isotope-labeled amino acids during protein synthesis. Cells can be cultured with various combinations of stable-isotope-labeled amino acids such as lysine or arginine. Tyrosine has been used in phosphoprotein studies of tyrosine residues. About five or six cell divisions are needed for complete labeling of proteins in cell cultures prior to experimentation. Labeled cells from control and treatment(s) lysates are combined and digested. Quantitation and identification are performed by LC-MS/MS.

H. Zhang, X.-J. Li, D. B. Martin, and R. Aerbersold, Identification and quantification of W-linked glycoproteins using hydrazide chemistry, stable isotope labeling and mass spectrometry, Nat. Biotechnol., 21 (2003) 660-666. 

In quantitative proteomics, two alternative strategies have been developed. The first one is based on 2-D PAGE combined with mass spectrometry for protein identification (Haynes and Yates, 2000). This method and current advances in the differential display of proteins by 2-D PAGE are discussed at length in another chapter of this book. The second approach exploits mass spectrometry in combination with stable isotope labeling for gaining accurate quantitative information on proteins. Quantitative MS via stable isotope labeling of proteins... 

The SI LAC approach has also been used to investigate metastatic prostate cancer development at the protein level (Everley et al., 2004). The fact that proteins showed altered concentration ratios by quantitative MS was confirmed by western blotting. In addition, proteomic approaches for quantitation of protein phosphorylation via SILAC combined with MS analysis have been described (Gruhler et al., 2005 Ibarrola et al., 2003, 2004). A recent study reports on identification as well as relative quantitation of in vivo mefhylation sites of proteins in HeLa cells by stable isotope labeling wifh C Hj-methionine (Ong et al., 2004). 

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