Racemization aspartic acid

Manley, W. R, G. H. Miller, and J. Czywczynski (2000), Kinetics of aspartic acid racem-ization, in Goodfriend, G. A., M. J. Collins, M. L. Fogel, S. A. Macko, and J. F. Wehmiller (eds.), Perspectives in Amino Acid and Protein Geochemistry, Oxford Univ. Press, New York, pp. 202-218. 

Radkiewicz et al.184 explored the mechanism of aspartic acid racemization by means of the DFT(B3LYP)/SCRF calculations. The DFT/SCRF calculations provided quantitative rationalization of the rapid racemization observed at succinimide residues in proteins. The proposed reaction mechanism was supported by the computed increase of the acidity of the succinimide residue in aqueous solution compared to gas phase. 

E. Fernandez, J.E. Ortiz, A. Perez Perez, E. Prats, D. Turbon, T. Torres, E. Arroyo Pardo, Aspartic Acid Racemization Variability in Ancient Human Remains Implications in the Prediction of Ancient DNA Recovery, Journal of Archaeological Science, 36,965 972 (2009). 

Table 8.1 Aspartic acid racemization dates from Californian Paleoindian Skeletons. (Reprinted with Permission from Bada et al., 1974 Tables 1 and 2. Copyright 1974 American Association for the Advancement of Science.)...

Table 8.4 Revised aspartic acid racemization dates for Californian Paleoin-dians. (After Bada, 1985 Table 1, reproduced by permission of the Society for American Archaeology from American Antiquity, 50 no. 3 1985.)...

Bada, J.L. (1985). Aspartic acid racemization ages of California Paleoindian skeletons. American Antiquity 50 645-647. 

Bada, J.L., Schroeder, R.A. and Carter, G.F. (1974). New evidence for the antiquity of man in North America deduced from aspartic acid racemization. Science 184 791-793. 

Masters, P.M. (1986b). Age at death determinations for the autopsied remains based on aspartic acid racemization in tooth dentin importance of postmortem conditions. Forensic Science International 32 179-184. 

Taylor, R.E., Ennis, P.J., Slota, P.J. Jr and Payen, L.A. (1989). Non-age-related variations in aspartic acid racemization in bone from a radiocarbon-dated late Holocene archaeological site. Radiocarbon 31 1048-1056. 

Van Duin, A.C.T. and Collins, MJ. (1998). The effects of conformational constraints on aspartic acid racemization. Organic Geochemistry 29 1227-1232. 

Waite, E.R., Collins, M.J., Ritz-Timme, S., Schutz, H.W., Cattaneo, C. and Borrman, H.I.M. (1999). A review of the methodological aspects of aspartic acid racemization analysis for use in forensic science. Forensic Science International 103 113-124. 

Goodfriend, GA., and Rollins, H.B. (1998) Recent barrier beach retreat in Georgia Dating exhumed salt marshes by aspartic acid racemization and post-bomb radiocarbon. J. Coast. Res. 14, 960-969. 

Zumberge, J. E. Hie effect of D-glucose on aspartic acid racemization. Paper presented at the Carnegie Institution of Washington Conference Advances in the Biogeochemistry of Amino Acids, Warren ton, Virginia, Oct. 29-Nov. 1, 1978. 

Feldman, P, L. and Rapoport, H Synthesis of optically pure A -tctrahydroquinolinic acids and hexahydroindolo[2,3-a quinolines from L-aspartic acid. Racemization on the route to vindoline. J. Org. Chem.. 51, 3882,... 

Of the various amino acids, aspartic acid has been the most widely used in fossil bone dating. This amino acid has one of the fastest racemization rates of the stable amino acids (21,22). At 20 C in bone, the half-life for aspartic acid racemization is 15,000 years. Thus, for most mid- or low-latitude sites the racemization rate of aspartic acid is... 

The effects of pH on racemization rates of free amino acids in aqueous solution are complex (21). However, when bone fragments were heated at 100°C in solutions of pH 2-9, the rate constant for aspartic acid racemization was essentially independent of pH (37). It was proposed that the phosphate from the bone s inorganic phase acts as a buffer. This same buffering action would take place in a bone under natural conditions of burial as well. 

Table I. Comparisons between Aspartic Acid Racemization and...

Age at Death Estimates Based on Aspartic Acid Racemization in Teeth... 

Racemization has recently been found to be an in vivo as well as a diagenetic reaction. We have demonstrated that D-aspartyl residues are accumulating in stable proteins during the human lifetime because of the high mammalian body temperature. Nonturned-over proteins which undergo racemization are tooth enamel (10), dentine (11), and proteins from the nucleus of the lens (12). The extent of aspartic acid racemization in these proteins could be used to calculate the age of the individual. 

The extent of aspartic acid racemization in the teeth of a skeleton can also be used, with certain limitations, to estimate the age of the individual at death. When the burial environment is relatively cold, the amount of postmortem racemization is negligible, so the d/l asp ratio in a tooth from a skeleton is a measure of the amount of in vivo racemization. 

For the aspartic acid racemization reaction, Equation 9 must be modified to... 

The calculated activation energy for aspartic acid racemization (20.8) is similar to the value reported by Darge and Thiemann (1971) for racemization of protein-bound aspartic acid. However, this value is about 10 kcal/mole less than the corresponding value reported by Bada (1971) for free aspartic acid determined at pH 7.6. In contrast, activation energies for alanine and phenylalanine residues in casein, determined at pH 12.5 were similar to those found for the same amino acids at pH 7.6. 

Table 11. Aspartic acid racemization and lysinoalanine (LAL) content of alkali-treated casein and acetylated casein.

Masters, P.M., Bada, J.L., and Zigler, J.S., Aspartic acid racemization in heavy molecular weight crystallines and water insoluble protein from normal human lenses and cataracts. Nature, 268, 71, 1977. 

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