Fibrous and Helical Calcite Crystals Induced by Synthetic Polypeptides ContainingO-Phospho-L-Serine andO-Phospho-L-Threonine

The modification of CaCO3 crystal growth by synthetic L-Ser(PO3H2) and L-Thr(PO3H2) containing polypeptides is described. The amino acids Gly, L-GlU, L-Asp, L-Ser, L-Ala, and L-Lys induced rhombohedral calcite with a rough surface. Dipeptides, Xaa-L-Ser(PO3H2) (Xaa = Gly, L-Glu, L-Asp, L-Ser, L-Ala and L-Lys) induced vaterite crystals in the lower [Ca2+]. on the other hand, L-Ser(PO3H2)-containing polypeptides formed spherical vaterite and fibrous calcite. The characteristic helical calcite was found in the presence of copoly[L-Ser(PO3H2)(75) L-Asp(25)] or poly[L-Ser(PO3H2)(3)-L-Asp]. Fibrous calcite, spherical vaterite, and helical calcite crystals were subjected to XRD and EDX analysis. XRD revealed the specific faces of these crystals. EDX spectra-and surface analysis visualized the localization of the polypeptides and CaCO3 components. Together with TEM and SAED data, we propose hypothetical growth mechanisms for the fibrous and helical calcite crystals. [GRAPHICS]