Retardation of racemization rates of amino acids incorporated into melanoidins

Abstract

Diagenetic reactions that affect the racemization of amino acids in fossils include hydrolysis of the original proteinaceous component and condensation of amino acids into “humic-like” materials. In this study, the consequences of condensation reactions for amino acid racemization rates are addressed. Aqueous solutions consisting of L-amino acids and D-glucose were heated ( 100°C) for up to 231 days. A comparison of racemization rates for amino acids in these solutions and in the resultant insoluble melanoidins indicates that the incorporation of amino acids into melanoidins retards racemization. In a sense, this retardation mimics the effect that has previously been attributed to the hydrolysis of proteinaceous material. An appraisal of the various diagenetic processes that may affect amino acid racemization rates in older fossil materials is essential for the refinement of geochemical research strategies that are dependent on this reaction.