Species origin identification of Oetzi’s clothing by MALDI-ToF mass spectrometry using tryptic hair digests

Articles

01 Apr 2009

Klaus Hollemeyer,^a Wolfgang Altmeyer,^b Elmar Heinzle^a and Christian Pitra^c
^aBiochemical Engineering Institute, Saarland University, Campus, D-66123 Saarbruecken, Germany
^bGene-Facts GbR, Science Park 1, Stuhlsatzenhausweg 67, D-66123 Saarbruecken, Germany
^cInstitute for Zoo and Wildlife Research, Postfach 601103, D-10252 Berlin, Germany

Introduction

In 2007 we introduced our method in Spectroscopy Europe describing the identification of furs by hair digest based matrix-assisted laser desorption/ionisation time of flight (MALDI-ToF) mass spectrometry (MS). It was shown that the so-called SIAM (Species Identification of Animals) method is a reliable, exclusively protein-based technique for mammalian species identification. Besides the identification of suspicious furs according to the EU-ban on domestic cat and dog fur trade, which came into effect from January 2009 and/or analogous further animal protections laws, quality checks of animal hair derived high priced clothing are routinely performed. Species attribution of unknown furs or wool from archaeological samples is a new application of this topic. The identification of archaeological hair samples is often difficult using classical methods like microscopy and/or polymerase-chain-reaction technique (PCR). Often the outer surface layers of the prehistoric hair (epi- and exocuticula) are damaged due to physical, chemical and/or microbial effects, especially if stored under suboptimal conditions. These drawbacks make microscopic determinations often uncertain. Although there are examples known for the partial survival of labile DNA in ancient hair samples, essential for the PCR identification technique. This nucleotide-based method often fails because of severe damage to the remaining DNA. Responsible for this are the same effects mentioned above, whereas fungal attacks to hair may even lead to exhausted shells, described as “ghost fibres”.

Keratin protein molecules as the structural base of hair are more resistant to those environmental stress factors than DNA and may be conserved with minor chemical degradations even under suboptimal conditions for thousands of years. The species determination of ancient furs was therefore a new challenge for the SIAM method to demonstrate its power of performance and to add a further application field.

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