Diagenetic reactions used most commonly in amino acid geochronology:
a) racemization of L- and D-enantiometers with a single chiral carbon (e.g. leucine, aspartic acid)
b) epimerization of L- and D- diastereomers (e.g. isoleucine)
Because the racemization / epimerization rate differs depending on the position of the amino acid in the peptide chain, the rate of hydrolysis influences the rate of racemization.

(Figure from Miller, G.H., and Brigham-Grette, J., 1989, Amino acid Geochronology: Resolution and Precision in Carbonate Fossils, IN, N. Rutter and J.Brigham-Grette and N. Catto, guest eds., "Applied Aspects of Quaternary Geochronology", Quaternary International. v. 1, p. 111-128.)

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