Achaeometrical Research in Hungary II., 1988

BIBLIOGRAPHY - SUMMARIES - DATING

acid contents in samples of known Age, determining the half life of Racemization and plotting the D/L ratio as a function of time, calibration curves were obtained. These curves can be used for the Age estimation of samples after determining their D- and Lamino acid content. The D/L ratio for 2 to 3 amino acids was determined for each sample and the mean value of estimated ages based on calibration curves was considered to estimate Age of the fossil samples. Csapó J., Csapó-Kiss Zs., Folestad, S., Orwar, O., Tivesten, A., Martin, T. G., Némethy S.: Age estimation of old carpets based on cystine and cysteic acid content = Analitica ChimicaActa (1995) 300. 1-3. 313-320. A method for evaluation of Age of wool carpets and textiles was developed based on the Age dependent alteration of amino acid composition of proteins. Samples of 23 wool Carpets and textiles of known Age, obtained from the Hungarian Museum of Industrial Arts and the Hungarian National Museum were analysed for amino acid content. Results were compared with data obtained for contemporary, untreated wool and wool carpet. The cysteic acid content of wool increased with Age. The contemporary wool carpet contained 0.31 g of cysteic acid in 100 g of protein. Comparable figures were 1.87 g for 550-year old carpet and 4.01-4.39 g for the 1600-1750-year old wool carpets. Cystine content decreased with Age corresponding figures being 7.88, 3.12, 1.19-0.97, respectively. Corresponding contents of methionine were 0.43, 0.21, and 0.20-0 and for tyrosine were 3.07, 2.11 and 0.20-0. Prediction equations were developed as linear regressions of Age of wool on cysteic acid, cystine and tyrosine contents. The 95% confidence intervals of estimates for two samples of unknown Age were estimates plus or minus 30 and 38 years. Csapó Ĵ. - Mariin, T. G., Csapó-Kiss Zs., Némethy S., Folestad, S., Tivesten, A.: Racemization of amino acids by using 6 molar hydrochloride acid for protein hydrolysis at elevated temperature = Analytica Chimica Acta (1997)... Racemization of free amino acids is considerably lower than that of amino acids bound in peptide. In the same experimental conditions, the rate of Racemization of free amino acids is only 20-80% of that of peptide bound amino acids. When using to traditional protein hydrolysis, Racemization was 1.2-1.6 times as high as that obtained at high temperatures (160-180 °C), under conditions ensuring total hydrolysis of the protein. This lower degree of Racemization may be explained by the fact that, at high temperatures, the protein hydrolyses more rapidly into free amino acids and the Racemization of free amino acids is considerably slower that of amino acids bound in polypeptides. When hydrolysis is conducted at lower temperatures for longer times, the amino acids bound in the peptide chain are exposed for a longer time to the effects actually causing Racemization. As a result, we may say that any factor which speeds up hydrolysis, will lower the degree of Racemization. Csapó J., Folestad S., Némethy S., Tivesten, A., Csapó-Kiss Zs.: Use of amino acid Racemization for fossil Age determination = Third International Congress on Amino Acids. Vienna, August 23-27 (1993). 279