El análisis de huella peptídica del colágeno mediante espectrometría de masas (ZooMS) para la identificación taxonómica en fauna arqueológica: desarrollo y retos actuales

Collagen is a protein that forms fibres that give elasticity and strength to bone. Protected by the mineral fraction of bone, collagen can remain virtually unchanged in fossil bones for thousands of years. Like all proteins, it is made up of amino acid sequences in a specific order dictated by the DNA of each organism. This property makes it possible to identify the species to which a bone fragment belongs using peptide fingerprint analysis, known in this application as zooarchaeology by mass spectrometry or ZooMS. This involves extracting the collagen from the bone and using certain parameters to check whether it is well preserved. It is then digested with an enzyme that splits the molecule at certain points to obtain a spectrum of fragments or peptides with different molecular weights by mass spectrometry. Given the highly conserved amino acid sequence of collagen, most of the peptides obtained by tryptic digestion are identical in all taxa, but some differ and are therefore useful for taxonomy. Identification is based on comparing the presence/absence of certain marker peptides with already available databases. The application of ZooMS for the identification of ancient remains started at the beginning of the 21st century and is still under development. Advances in the development of this technique allow the identification of bone fragments from mammals and other vertebrates, in many cases down to the genus level. However, for certain taxa it is not yet possible to distinguish genera within the same family. Work is currently underway to expand the number of well-characterised taxa, improve the definition of peptides for the different taxonomic groups, and standardise technical processing and databases. In this paper, we present as an example the identification of five Upper Pleistocene bone fragments from Cova Eirós (Lugo, Galicia) and discuss the applications, limitations and progress of this new zooarchaeological technique.