Species identification of Oetzi's clothing with matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry based on peptide pattern similarities of hair digests

Abstract

Identification of ancient biological samples from the 1991-discovered and more than 5300-year-old Tyrolean mummy, also called iceman or Oetzi, is very difficult. The species of origins of four animal-hair-bearing samples of the accoutrement of the mummy not yet diagnosed were identified by a special proteomics method. Ha 43/91/130 and Ha 6/91, two samples from his coat, and Ha 5/91, a sample from his leggings, were assigned to sheep. The upper leather of his moccasins, Ha 2/91, was made from cattle. Despite the enormous age of these samples with partial (bio)chemical alterations, reliable identification was possible using a recently developed matrix-assisted laser desorption/ionization time-of-flight mass spectrometric ((MALDI-TOF MS)-based analytical method. The method is exclusively based on the analysis of proteins and uses minute amounts of peptides directly derived from tryptic hair digests without any separation or enrichment steps. Unknown species are identified by comparison of their peptide ion patterns with known spectra stored in existing databases. Hereby, the correlation distance, a form of Euclidean distance, and deduced parameters are used to measure similarities. If more than one potential hit remains, specific diagnostic peptide ions are used to stepwise exclude incorrect matches. These ions are specific for orders, families, subfamilies/genera and/or even species. Peptide mass fingerprinting data combined with those from collision-induced dissociation spectra (combined MS & MS/MS) were used for interpretation with the MASCOT search engine and the NCBI database to find the potential parentage of hair proteins. For this technique, selected precursor ions were identified as specific diagnostic peptide ions.

Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry combined with multidimensional scaling, binary hierarchical cluster tree and selected diagnostic masses improves species identification of Neolithic keratin sequences from furs of the Tyrolean Iceman Oetzi

“…SIAM present study Quiver Microscopy Groenman-van Waateringe and Goedecker-Ciolek [55] before reconstruction Microscopy Lange [10] Brown bear (Ursus arctos) Cap Microscopy Groenman-van Waateringe and Goedecker-Ciolek [55] Shoe (sole) Microscopy Groenman-van Waateringe and Goedecker-Ciolek [55] Canid species Leggings SIAM present study Sheep (Ovis aries) Coat SIAM Hollemeyer et al [14] dto. SIAM present study Leggings SIAM present study Goat (Capra hircus) Coat SIAM Hollemeyer et al [14] dto. SIAM present study Loin cloth Microscopy Groenman-van Waateringe and Goedecker-Ciolek [55] Leggings Microscopy Groenman-van Waateringe and Goedecker-Ciolek [55] dto.…”

“…[12,13] In a previous study exclusively sheep and cattle were identified from four samples of his coat, leggings and a shoe, respectively. [14] An agro-pastoral society with hunting activities, however, can be assumed, if additional use of wild game furs can be confirmed. This could be a hint for a venison nutrition support as well as for a potential defence of grazing herds against carnivore attacks.…”

“…[37] Hair samples from the Oetzi samples however show explicit molecular damage of the keratins due to their storage under suboptimal conditions. [14,38] Such conditions together with harsh tanning procedures could be the reason why aDNA-based species identification of the fur samples has not been successful so far.…”

“…The keratin-based method used in this study (SIAM = Species Identification of Animals using MALDI-TOF mass spectrometry) was developed for the identification of native feathers, down and hair. [14,46,47] Pmfs from digests of intact hair show species-specific differences in their peptide patterns. Specific calculation of their spectral similarities is a measure for their zoological relationship shown by subsequent graphic visualization routines.…”

Alkali Treatments of Woven Lyocell Fabrics

“…For instance, Babylonia was the first country to process and trade in wool (Babylonia = land of wool) and also, the proof of using leather of different skin in clothes and shoes by discovery of the oldest European mummy; Ötzi the Iceman -man who lived about 5,300 years ago, on the border between Austria and Italy. (Hollemeyer et al, 2008;Kutschera & Rom, 2000) Regenerated cellulose fibres are the first artificial fibres ever made. Processes capable of dissolving the cellulose derived from wood or cotton linters were first discovered by Schnöbein (1845, nitrocellulose soluble in organic solvents), Schweizer (1857, cellulose in cuprammonium solution), Cross, Bevan and Beadle (1885, cellulose sulfidized in sodium hydroxide; 1894, cellulose triacetate in chloroform) followed by commercial production of acetate fibres started in 1919; in 1955 they were joined by triacetate.…”