THE SIGNIFICANCE OF A GEOCHEMICALLY ISOLATED INTRACRYSTALLINE ORGANICFRACTION WITHIN BIOMINERALS

In studies of organic matter in fossil biominerals, there has been a w idespread failure to distinguish between the organic matrix and organi c matter trapped within the crystal elements. The existence of chemica lly isolated (intracrystalline) proteins are indicated by the persiste nce of amino acids after prolonged treatment with a strong chemical ox idant (NaOCl). The geochemical significance of these residual amino ac ids is illustrated by the re-analysis of aberrantly young D-aile/L-ile ratios (0.142 +/- 0.042, n = 4) of amino acids from a land snail (Cep aea sp.) collected from Tattershall Thorpe in Lincolnshire. Following NaOCl treatment the D-aile/L-ile ratio increased (0.178 +/- 0.014, n = 5), while both the total amino acid concentration and the variance de clined. (C) 1996 Elsevier Science Ltd.