Role of Water in CaCO3 Biomineralization

Biomineralization occurs in aqueous environments. Despite the ubiquity and relevance of CaCO3 biomineralization, the role of water in the biomineralization process has remained elusive. Here, we demonstrate that water reorganization accompanies CaCO3 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 CaCO3 mineralization. Our results show that, while the protein structure remains unchanged, the structure of interfacial water is perturbed differently in the presence of both Ca2+ and CO32- compared to the addition of only Ca2+. 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.

Automated summary

Through specific experiments, it was found that water plays an important role in the CaCO3 biomineralization process for sea urchin spine generation. The study results show that the structure of interfacial water is perturbed differently when Ca2+ and CO32- are present together compared to only adding Ca2+. These findings support a nonclassical mineralization pathway for sea urchin spine generation and highlight the importance of protein hydration in biomineralization.