Citation
Torres Pérez-Hidalgo, Trinidad José and Ortiz Menéndez, José Eugenio and Llamas Borrajo, Juan F. and Canoira López, Laureano and García García, María Jesús
(2001).
Geochemical evolution of pleistocene bears dentine amino acids.
"Chirality", v. 13
(n. 8);
pp. 517-521.
ISSN 1520-636X.
Abstract
A linear correlation was established between aspartic acid racemization
ratio from cave bear dentine collagen and absolute dating. The high correlation coefficient
obtained allowed age calculation through amino acid racemization. Aspartic acid
and glutamic acid racemization kinetics have also been explored in dentine from a North
American black bear (Ursus americanus Pallas). Three sample sets were prepared for
kinetic heating experiments in nitrogen atmosphere: one water soaked, one with a
water-saturated nitrogen atmosphere, and one without any moisture. It was possible to
show that the presence of water is a factor controlling amino acid racemization rate. The
aspartic acid in a heating experiment at 105° C shows an "apparent kinetics reversal"
which can be explained by a progressive hydrolysis of amino acid chains (proteins and
polypeptides). Because of t h e low potential of collagen preservation over long periods of
time, the apparent kinetics reversal phenomenon will not affect the dating of old material
where no traces of collagen remain. An apparent kinetics reversal was not observed in
glutamic acid, which racemizates more slowly