Diagenesis of the Organic Matrix in Anadara trapezia during the Late Quaternary: Preliminary Findings

Margaret J. Whitelaw*, Barry D. Batts, Colin V. Murray-Wallace, Christopher R. McRae

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The concentration of amino acids found in the soluble organic matrix of modern and fossil shell of Anadara trapezia is quantified in this study. Results indicate that 91% of the total amino acids present in the soluble organic matrix are lost within 4,000 years, at an average rate of 3.25 × 10-3 pmol/μg per year. Over the next 2,000 years a further 6.3% are lost at an average rate of 4.49 × 10-4 pmol/μg per year and for a further 119,000 years 0.9% of material was lost at an average rate of 1.07 × 10-6 pmol/μg per year. Aspartic acid, glutamic acid, glycine and alanine were found to be present with the highest concentrations having a mean concentration of 28.3 pmol/μg. These amino acids were also found to be more readily hydrolyzed from the soluble organic matrix. After 4,000 years their concentrations had dropped to be within the same range as all amino acids remaining in the organic matrix with a mean concentration of 1.3 pmol/μg. Amino acid concentrations remained at this level for the next 119,000 years with little further losses. The degree of racemization from L form to D form, i.e. the D/L ratio of amino acids was found to be related to concentration and amino acids such as aspartic acid, with high initial concentration also show faster racemization rates. Aspartic acid hydrolyses and racemizes at a faster rate than other amino acids leading to the hypothesis that the more aspartic acid molecules present in the protein strand, the greater the chance that aspartic acid will be in the optimum position for hydrolysis and racemization.

Original languageEnglish
Pages (from-to)225-234
Number of pages10
JournalProceedings of the Linnean Society of New South Wales
Volume2001
Issue number123
Publication statusPublished - 2001

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