Novel spectroscopic deconvolution procedure for complex biological systems: vibrational components in the FT-Raman spectra of ice-man and contemporary skin

Abstract

Skin samples from the corpse of a late-Neolithic man (5200 years BC) found in a glacier in Oetzal, commonly known as the Ice-man, have been analysed using FT-Raman spectroscopy. Good quality spectra have been obtained and compared with those from contemporary freeze-dried stratum corneum, using a time-dependent FT deconvolution method. This provided vibrational spectroscopic information about unresolved or partially resolved features including band halfwidth data, which are particularly useful for identifying membrane order–disorder variations between ancient and modern tissues. At the molecular level, the majority of the vibrational modes present in contemporary tissue were also evident in the spectra of the ancient skin, although Ice-man skin differed from modern skin in the ν(C—H) stretching region, attributable to the oxidation of alkenic bonds. Additionally, some degradation of the protein components (i.e. keratin) was indicated by the reduction in vibrational intensity of the amide I[ν(C—O)] and amide III [ν(C—N) and δ(N—H)] modes.