Paleoproteomics of pottery food residues reveals plant cupin superfamily proteins preserved for thousands of years

Abstract

This study focuses on ancient proteins preserved as carbonized food residues on pottery from East Asian archaeological sites associated with plant use. Food residues on pottery vessels were carbonized hundreds to thousands of years ago when plant and animal materials were heated; so, only trace amounts of proteins and other biomolecules are expected to remain. Paleoproteomic analysis showed that many peptides derived from cupin superfamily proteins of plant origin, such as the glycinin proteins of the genus Glycine, the 11S globulin protein from the Juglandaceae family, and the glutelin protein from the genus Oryza, were detected in the charred food residues. Lipid and isotope data were consistent with the proteomic results. Furthermore, 3D protein structure mapping showed that the detected peptides fall within β-barrel regions of the proteins, the structurally stable cores of these seed storage proteins. Thus, pottery foodcrusts preserved plant cupin proteins over 7,900–2,500 years. Subject areas: Paleobiology, Paleobiochemistry, Archeology