C experiments to mimic diagenesis at burial temperature. The outcomes highlighted a difference in between patterns of degradation at low and higher temperature and thus we advise caution for the extrapolation of protein breakdown rates to low burial temperatures for geochronological purposes when relying solely on kinetic data. 2012 Elsevier B.V. Open access under CC BY license.1. Introduction The extent of protein diagenesis can provide a reliable estimate of the age due to the fact death of subfossil biominerals where the original protein fraction is preserved and has undergone in situ degradation (e.g. Brooks et al., 1990; Curry et al., 1991; Sykes et al., 1995; Penkman et al., 2008). Protein breakdown may be quantified when it comes to peptide bond hydrolysis, amino acid racemisation (the interconversion reaction in between L and D enantiomers of an amino acid) and amino acid decomposition (to either other amino acids or other organic compounds). Even so, the partnership involving time elapsed since death in the organism and the extent of breakdown is complicated and requires correct evaluation of patterns of diagenesis as a function of each time and temperature. The lack of details about this partnership hampers the precision and accuracy of protein diagenesis as a numerical geochronological tool (e.g. Wehmiller, 1993).Higher temperature experiments have traditionally been applied to induce artificial protein diagenesis within laboratory timescales (e.g. Hare and Mitterer, 1969). The reliability of kinetic experiments for describing diagenesis in subfossil biominerals has been investigated within a variety of studies (e.g. Wehmiller, 1980; Goodfriend and Meyer, 1991; Collins and Riley, 2000; Miller et al., 2000; Clarke and MurrayWallace, 2006; Kaufman, 2006) which have highlighted a number of the issues affecting the use of kinetic experiments to derive an adequate model of protein breakdown, and particularly amino acid racemisation: (i) the use of mathematical expressions to describe racemisation typically underestimate the interplay of this with other diagenesis reactions (i.e. hydrolysis, decomposition); (ii) the observation of outcomes (i.e. Arrhenius parameters for observed effects for instance racemisation and hydrolysis) limits the reliability of higher temperature experiments if the underlying concurrent reactions that contribute for the observed effect have diverse activation energies; (iii) the loss of totally free amino acids (and soluble peptides) from an open technique results inside the underprediction not merely of rates Corresponding author. Tel.: 4 (0) 1904 328559. E mail address: beatrice@palaeo.Price of 1620575-06-5 eu (B.2,4,6-Trichloro-5-cyanopyrimidine manufacturer Demarchi).PMID:24733396 18711014 2012 Elsevier B.V. Open access beneath CC BY license. http://dx.doi.org/10.1016/j.quageo.2012.08.B. Demarchi et al. / Quaternary Geochronology 16 (2013) 158eof hydrolysis but additionally racemisation, inside the latter case since the no cost amino acids are the most highly racemised. Racemisation is thought to proceed by means of the basecatalysed abstraction of the aproton in an amino acid along with the formation of a carbanion intermediate (Neuberger, 1948). Consequently, very alkaline environmental conditions may well play an essential role, but the impact of pH is most likely to become less significant than that of temperature (see Orem and Kaufman, 2011). At no cost amino acids in aqueous answer, this reaction could be described by firstorder reversible kinetics (FOK; Bada and Schroeder, 1975). Nevertheless, in a series of higher temperature investigations, the use of mathematical transforma.