Calcium-Induced Molecular Rearrangement of Peptide Folds Enables Biomineralization of Vaterite Calcium Carbonate

Proteins can control mineralization of CaCO₃ by selectively triggering the growth of calcite, aragonite or vaterite phases. The templating of CaCO₃ by proteins must occur predominantly at the protein/CaCO₃ interface, yet molecular-level insights into the interface during active mineralization have been lacking. Here, we investigate the role of peptide folding and structural flexibility on the mineralization of CaCO₃. We study two amphiphilic peptides based on glutamic acid and leucine with β-sheet and α-helical structures. Though both sequences lead to vaterite structures, the β-sheets yield free-standing vaterite nanosheet with superior stability and purity. Surface-spectroscopy and molecular dynamics simulations reveal that reciprocal structuring of calcium ions and peptides lead to the effective synthesis of vaterite by mimicry of the (001) crystal plane.