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Aspartic acid racemization and protein diagenesis in corals over the last 350 years

Authors
Journal
Geochimica et Cosmochimica Acta
0016-7037
Publisher
Elsevier
Publication Date
Volume
56
Issue
10
Identifiers
DOI: 10.1016/0016-7037(92)90176-j
Disciplines
  • Biology

Abstract

Abstract D/L aspartic acid values from a 350-year time series of annual growth bands of a living colony of the coral Porites australiensis show a very regular pattern of increase with age. The initial rate of racemization is extraordinarily rapid (0.6% per year) but slows in older growth bands to 0.04% per year (4% per century). The skeletal proteins show progressive hydrolysis with increasing age, with free aspartic acid comprising 16% of the total aspartic acid in the 350-year-old band. The proteins are unusually rich in aspartic acid (nearly 50 mol%). The relative weakness of the peptide bonds formed by aspartic acid moieties is probably responsible for the rapid hydrolysis and consequent rapid racemization of aspartic acid. Racemization analysis provides a means for checking for sections of missing bands in corals and for screening of prospective samples for U-Th dating.

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