Chemical recognition of carbonate anions by proteins involved in biomineralization processes and their influence on calcite crystal growth

In this work, we report the purification and characterization of struthiocalcins (SCA-1 and -2), two proteins isolated from the intramineral part of the ostrich's eggshell. To obtain a better insight about their solubility behavior at different temperatures in water and in buffer solution, dynamic light scattering experiments were carried out. We studied the influence of the intramineral proteins SCA-1 and SCA-2 as well as the two other proteins present in eggs such as ovocleidin-17 (OC-17) and lysozyme (Lys) on the crystal growth behavior of calcium carbonate (calcite). This study showed important changes in the crystal habit and the nucleation process of calcium carbonate. Finally, the electrochemical methods were analytically used to confirm the interaction observed in the crystallization experiments. These results sorted out our dilemma about the selectivity and chemical recognition of proteins present in the eggshell for calcium or carbonate ions.