Etic parameters for Ser and Asx decomposition, obtaining values of Ea Asx 109 kJ/mol and Ea Ser 103 kJ/mol (Table 6). The modelfree approach was also employed to identify relative decomposition rates of Asx and Ser at higher temperature (80e 140 C); the [THAA]aa/[Total THAA]0 aspect (defined above) was plotted against the “scaled” logarithm of time and the efficient Arrhenius parameters were estimated (Table 7). The values derived with this method are larger (Ea Asx w146 kJ/mol, Ea Ser w 131 kJ/ mol) than these obtained by using Eq. (4). The effective activation energy of decomposition of Ser to Ala was estimated by fittingTable 6 Apparent decomposition prices (k, s) for Asx and Ser obtained by applying Eq. (four); coefficients of determination (R2) for the linear regression at each and every temperature; kinetic parameters (Ea and also a) and coefficients of determination (R2) for the Arrhenius relation. R2 R2 pFOK k k k 140 C 140 C 110 C 110 C 80 C (s) (s) (s) Asx Ser 2E06 0.93 1E05 0.91 1E07 0.87 7E07 0.90 R2 Ea A 80 C (kJ/mol) (s) 108 103 R9E09 0.60 6E08 0.9E7 0.99 1E8 0.B. Demarchi et al. / Quaternary Geochronology 16 (2013) 158eFig. 9. Powerful activation energies (Ea, kJ/mol) obtained with all the “scaling” approach for racemisation and hydrolysis for several amino acids; note that Ea racemisation Ea hydrolysis.system can be examined as they proceed by plotting the FAA of a provided amino acid against the D/L values from the same amino acid. This facilitates comparison in between the extent of diagenesis inside the hightemperature kinetic experiments and fossil biominerals. Here we compare the extent of Asx and Val diagenesis in the closedsystem proteins isolated from Patella shells of Holocene (the Scottish sites of Archerfield, Whitegate, Coire and Sand) and Middle Pleistocene ages (Easington raised beach, MIS 7) using the hightemperature information described within this study from both the “bulk” powders sample and the “rim only” powders (Fig. 10). This plothighlights clearly that the patterns of Asx diagenesis in bleached Patella shells are diverse at low and high temperatures. Soon after the initial stages of diagenesis (up to w20 FAA in Fig. 10a and FAA D/L w0.2 in Fig. 10c), the fossil samples deviate in the trajectories of your 140 C and 110 C experiments (see also Fig.Boc-NH-PEG11-NH2 web A in Supplementary Information 4, displaying that the fossil samples also follow a unique trajectory from modern day unbleached Patella powders, heated at 140 C). They seem to stick to a similar trajectory for the 80 C information with regards to the release of FAA (Fig. 10a), however the trajectory for Asx racemisation is strikingly various at high and low temperature (Fig. 10c). Consequently, hightemperature experiments don’t necessarily mimic Asx diagenesis at low temperatures (see also Goodfriend and Meyer, 1991).BuyFmoc-D-Dab(Boc)-OH Conversely, related patterns of Val diagenesis could be observed across the diverse temperatures with regards to extent of hydrolysis versus THAA racemisation (Fig.PMID:33752267 10b). The plot of Val FAA D/L versus THAA D/L (Fig. 10d) is less informative for Holocene samples as a result of the low concentrations of FAA Val recovered, which are reflected in variable D/L values. The Easington specimens fall at decrease THAA D/L values than the hightemperature data for comparable FAA D/L values; nonetheless, exactly the same plot shows that for samples degraded at reduce temperatures (i.e. samples heated for 720e960 h for the 80 C experiment), FAA DLs are as high as 0.6, and they subsequently decrease with growing heating time.
