Dresden 2006 – scientific programme

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AKB: Biologische Physik

AKB 40: Poster Session II

AKB 40.30: Poster

Wednesday, March 29, 2006, 16:30–19:30, P3

Purification and characterisation of nacre proteins and their interaction of nacre proteins with CaCO₃ at the molecular scale — •Laura Treccani, Fabian Heinemann, and Monika Fritz — Institut of Biophysics, University of Bremen, Germany

Nacre (mother of pearl) of certain molluscs furnishes an elegant model to investigate biomineralizing processes. Nacre is a polymer-ceramic composite material consisting mainly of CaCO₃ and biomolecules (chitin and proteins). It shows a highly ordered hierarchical structure consisting of parallel layers of aragonite tablets (500 nm thickness) alternated with layers of organic material (10 nm thickness). Nacre has a high mechanical strength and resistance against corrosion in seawater that far exceeds the properties shown by the inorganic CaCO₃ mineral. Organic molecules are necessary for a controlled nucleation and growth of the material. The role of several water-soluble proteins purified from nacre of H. laevigata has been investigated. Crystallization experiments were performed with the AFM (Atomic Force Microscope) in aqueous solution on a calcite surface and with the ammonium carbonate method. It has been elucidated that each protein influences the crystal growth in a different way. Some proteins can act as nucleators, where others can act as inhibitors. Recently small proteins directly incorporated into the mineral phase have been detected. The characterisation of the single biomolecules and their roles in self-organizing mechanisms of nacre formation could lay the basis for a better understanding of biomineralization and the development of new synthetic biomaterials.