[In vivo amino acid racemization: possible role in the molecular aging of proteins (author's transl)].

The in vivo aspartic acid racemization was observed in proteins having slow turnover rates and found in calcified tissues (tooth) as well as in soft tissues (lens). It can be used as a biochronological tool for estimating the age of a person, or as a mean for evaluating the in vivo lifetime of certain proteins. Racemization can be considered as the cause of accumulating configurational errors within the non-renewable, already synthetized molecules, and therefore probably constitutes a mechanism for molecular aging.