AIC's 47th Annual Meeting

The introduction of proteomics to archaeological proteins has brought a new set of techniques to characterize protein fibers and address issues such as techniques of fabrication of textiles and degradation of protein fibers. Recently applied to metal threads, a method for small scale sample extraction and nano liquid chromatography Orbitrap tandem mass spectrometry (nanoLC-Orbitrap MS/MS) analysis was developed to identify the protein substrate of a metal-wrapped thread from a 14th century Italian textile . Organic metal threads were made with an organic substrate, either cellulosic (paper) or proteinaceous (leather, parchment or membranous tissues, often the stomach or intestinal walls of animals) and were a common variety of metal thread in textiles until the 15-16th c. The metal (most frequently gold, silver or alloys) was applied to the organic substrate using either an additional adhesive (bole, glue, gum, or eggs) or the natural exudates of the substrate. Tests on membrane standards using proteomics have determined that collagen peptides were the best markers to identify the animal species of origin, while tissue specific proteins, such as smooth muscle proteins detected in gut tissues, could be used to distinguish between membrane and skin types. Egg proteins can also be detected alongside the substrate if used as a binding material and differentiated as egg white or yolk1. The study of proteinaceous metal threads constitute a very wide topic as the threads were made and/or used in many localities, from Europe to the Middle East, to Central and East Asia. All previous attempts to classify textiles and assign them to different workshops by the study of metal threads were based on the morphological characteristics of metal threads, and the metal composition of coatings. Proteomics analysis will add another dimension and help in the research of the provenance of the threads and/or fabrics. Current results on the proteomics analysis of organic metal threads from the Cooper Hewitt Smithsonian Design Museum and other collections will be presented in this paper.