Proteome variation with collagen yield in ancient bone

Isotope analyses are some of the most common analytical methods applied to ancient bone, aiding the interpretation of past diets and chronology. For this, the evaluation of “collagen” yield is a routine step that allows for the selection of the specimens that are adequate for subsequent analyses, and samples with below ~1% yield normally discarded. Additionally, during the “collagen extraction” procedure, several sample fractions are generated and subsequently discarded but could contain proteins of analytical interest. In this study we evaluated the proteome variability of different fractions generated during the “collagen extraction” process of 29 samples, and their correlation with the collagen yield. We found that these fractions contained a significant amount of both collagenous and non-collagenous protein (NCP) spectra and that these were not correlated with the collagen yield. The variety of the extracted NCPs was comparable with that normally obtained from ancient samples, and the information obtained can be used to conduct species identification, phylogenetic studies, isotopic analyses and may be used to perform radiocarbon dating on the specimens. Overall, these findings suggest that not only is there value in retaining the fractions typically discarded as waste, but that low collagen yield specimens can still yield useful information.