Role of Water in CaCO<sub>3</sub>Biomineralization
Hao Lü, Yu-Chieh Huang, Johannes Hunger, Denis Gebauer, Helmut Cölfen, Mischa Bonn
Abstract
Biomineralization occurs in aqueous environments. Despite the ubiquity and relevance of CaCO 3 biomineralization, the role of water in the biomineralization process has remained elusive. Here, we demonstrate that water reorganization accompanies CaCO 3 biomineralization for sea urchin spine generation in a model system. Using surface-specific vibrational spectroscopy, we probe the water at the interface of the spine-associated protein during CaCO 3 mineralization. Our results show that, while the protein structure remains unchanged, the structure of interfacial water is perturbed differently in the presence of both Ca 2+ and CO 3 2-compared to the addition of only Ca 2+ . This difference is attributed to the condensation of prenucleation mineral species. Our findings are consistent with a nonclassical mineralization pathway for sea urchin spine generation and highlight the importance of protein hydration in biomineralization.