Amino acid composition of degraded matrix collagen from archaeological human bone.

In relation to specific burial conditions, the degree of preservation of archaeological bone collagen shows significant variation which cannot be discerned sufficiently by histological inspection. Thus the validity of archaeometric data cannot be confirmed as such and further proof is required. This study deals with diagenetic modifications of extractable collagen from archaeological human bones (14 skeletal series from various locations, inhumation periods and modern skeletal material). The content of proteinogenic and not-proteinogenic amino acids was determined by amino acid analysis compared to experimentally degraded scleroprotein. The resulting amino acid composition of the insoluble extracts differs from native collagen in relation to the specific skeletal series. Five different qualitative categories could be distinguished. Rare and carbon rich amino acids preferably disappeared in the archaeological specimens. Essential and experimentally validated decomposition phenomena as e.g. selective degradation of specific amino acids were confirmed and an example is given for the differentiation of valid from diagenetically altered carbon isotopic signatures by amino acid analysis.