Is manganese bound to the protein or to the mineral fraction of Cypraea snail shell matrix?

SOLDATI, ANALIA L.; BAUMANN, WOLFRAM

Mainz, Germany

Workshop; Workshop des DFG-Graduiertenkollegs 826 über Elementspeziation; 2005

University of Mainz

The element Mn is present in shells of marine animals at concentrations of 10-50 ppm. Our investigations in Cypraea tigris snails have already demonstrated that manganese is not only Mn2+ replacing Ca2+ in the aragonite shell structure, but is organically bound, too. Further characterization of this organic fraction needs dissolvation of the highly dominant CaCO3 fraction. The respective process is complicated and must be optimized so as not to destroy the manganese-organic species. The CaCO3 is dissolved by a titration process with HCl controlling carefully pH steps around 4.5 in large water volumes, protecting from bacterial attack by NaN3 and from protease attack by Aldrich® Protease Inhibitor Cocktail. Reduction to useful volumes was done by ultracentrifugation filtration trough a >3kDa membrane and CaCl2 and the protecting agents have then been removed by exhaustive dialysis against MilliQ water with a >3kDa membrane, too. Final concentration was by freeze drying. Firsts analysis of the >3kDa organic fraction then will be done by combined methods such like HPLC-UV-ICP-MS or Protein HPLC-MS in order to elucidate further the type of binding of manganese to the organic fraction; strong respective correlations have already been shown in a previous step of this work.