DNA and proteins are now almost routinely being retrieved from sediments and archaeological artefacts. Despite the realization that adsorption of DNA molecules onto the surfaces of minerals can significantly decrease the DNA and protein decay rate, the longevity of mineral bound biomolecules is a still-standing frontier. Recently it was shown that peptide sequences in eggshell proteins persist to 3.8 Ma in Africa, implying that protein sequences will span the whole of human history in all parts of the world. Ancient protein sequences, therefore, persist beyond the lipid or DNA sequence and can be used to identify organisms (ZooMS), identify specific tissues, sex individuals, and identify tissue responses to disease. Understanding the protein-mineral interaction and environmental preservative conditions of adsorbed biomolecules – proteins can thus allow us to a) target such environments for paleoecological and palaeogenetic studies and; b) serve as a quantitative tool for assessing protein sequence migration i.e. ancient microbial communities.
To date, we only have a qualitative idea of how solution composition affects the protein-mineral adsorption/desorption at the bulk level, and we have no quantitative insight into the single bond level energetics as well as the nature and fraction of the interacting bonds. With ProArc I will: a) assess the proteins preservation state in archaeological samples like calculus and ceramics and other fossil samples. I will also: (b) quantify the Gibbs free energy (ΔGbu) and kinetic bond parameters of in vitro protein-mineral interactions; and (c) examine the nature, fraction and stability of interacting bonds of in vitro protein-mineral associations at the bulk level. (d) Finally, I will make a conceptual model for addressing the characteristics and longevity of different protein-mineral systems.
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