Amino acids isotopic analysis

Amino Acids publishes contributions from all fields of amino acid research analysis, separation, synthesis, biosynthesis, cross linking amino acids, race-mization/enantiomers, modification of amino acids as phosphorylation, methylation, acetylation, glycosylation and nonenzymatic glycosylation, new roles for amino acids in physiology and pathophysiology, biology, amino acid analogues and derivatives, polyamines, radiated amino acids, peptides, stable isotopes and isotopes of amino acids. 

Van Klinken, GJ. 1991 Dating and Dietary Reconstruction by Isotopic Analysis of Amino Acids in Fossil Bone Collagen—with Special Reference to the Caribbean. Ph.D. dissertation. University of Groningen, The Netherlands. 

Since it is possible to differentiate well-preserved from badly preserved collagen through amino acid analysis and gel electrophoresis, it is also possible to determine which bone samples are likely to give erroneous isotopic ratios. At least for 8 C, it should be possible to estimate the in vivo isotopic signature by correcting the changed amino acid concentrations of the collagen extract. This way, a reasonable approach to the reconstruction of pale-odiet should be possible. 

NOTE ADDED IN PROOF This manuscript had been submitted shortly after the presentation of the paper at the Fourth Advanced Seminar on Pale-odiet, 1994. Ongoing research, especially stable isotope analysis of single amino acids from inoculated and non-inoculated marten bones (same specimens as in this paper) further and strongly support our conclusion that bacterial modifica-tion causes substantial shifts in collagen stable isotope ratios (Balzer et fl/. 1997). 

Paleodiet studies have focused on the analysis of collagen, due to its ability to survive in ancient bone. Like all proteins, collagen is composed of amino acid (AA) units present in relatively constant proportions characteristic of the specific protein. The isotopic composition of a sample of collagen is the weighted average of the 5 C values of each of the constituent amino acids. 

Veenstra, T. D. Martinovic, S. Anderson, G. A. Pasa-Tolic, L. Smith, R. D. Pro-teome analysis using selective incorporation of isotopically labeled amino acids. /. Am. Soc. Mass Spectrom. 2000,11, 78-82. 

The aims of this contribution are to (i) consider the theoretical principles underlying the use of compound-specific stable isotope analysis in archaeology (ii) consider the practical aspects of undertaking compound-specific stable isotope analyses and (iii) demonstrate the value of linking the structures of amino acids, fatty acids and/or sterols, to their compound-specific stable isotope values to achieve new insights into variations in metabolism and environment in order to enhance archaeological interpretations. 

GC-C-IRMS instrumentation enables the compound-specific isotope analysis of individual organic compounds, for example, n-alkanes, fatty acids, sterols and amino acids, extracted and purified from bulk organic materials. The principle caveat of compound-specific work is the requirement for chemical modification, or derivatisation, of compounds containing polar functional groups primarily to enhance their volatility prior to introduction to the GC-C-IRMS instrument. Figure 14.7 summarises the most commonly employed procedures for derivatisation of polar, nonvolatile compounds for compound-specific stable isotope analysis using GC-C-IRMS. 

GC-C-IRMS enables amino acids to be separated by GC, combusted on-line, for stable isotopic analysis thereby avoiding manual preparative steps (see Figures 14.5, 14.8 and 14.9). The 513C values of individual collagen amino acids are highly robust and by... 

Fogel, M. L. and Tuross, N. (2003) Extending the limits of palaeodietary studies of humans with compound specific carbon isotope analysis of amino acids. Journal of Archaeological Science 30, 535 545. 

Macko, S. A., Uhle, M. E., Engel, M. H. and Andrusevich, V. (1997) Stable nitrogen isotope analysis of amino acid enantiomers by gas chromatography combustion/isotope ratio mass spectrometry. Analytical Chemistry 69, 926 929. 

McCullagh, J. S. O., Juchelka, D. and Hedges, R. E. M. (2006) Analysis of amino acid 13C abundance from human and faunal bone collagen using liquid chromatography/isotope ratio mass spectrometry. Rapid Communications in Mass Spectrometry 20, 2761 2768. 

Metges, C. C. and Daenzer, M. (2000) 13C gas chromatography combustion isotope ratio mass spectrometry analysis of N pivaloyl amino acid esters of tissue and plasma samples. Analytical Biochemistry 278, 156 164. 

Styring, A. K., Sealy, J. C. and Evershed, R. P. (in press) Resolving the bulk 81SN values of ancient human and animal bone collagen via compound specific nitrogen isotope analysis of constituent amino acids. Geochimica et Cosmochimica Acta. 

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