Self-assembled peptide P11-4 interacts with the type I collagen C-terminal telopeptide domain and calcium ions

Evaluate molecularly the role of P₁₁-4 self-assembly peptide in dentin remineralization and its interaction with collagen I.

The calcium-responsive P₁₁-4 peptide was analyzed by intrinsic fluorescence emission spectrum, circular dichroism spectrum (CD), and atomic force microscope (AFM). Differential light scattering was used to monitor the nucleation growth rate of calcium phosphate nanocrystals in the absence or in the presence of P₁₁-4. AFM was used to analyze the radial size (nm) of calcium phosphate nanocrystals formed in the absence or in the presence of P₁₁-4, as well as to verify the spatial structure of P₁₁-4 in the absence or in the presence of Ca²⁺.

The interaction of Ca²⁺ with the P₁₁-4 (K_D = 0.58 ± 0.06 mM) promotes the formation of β-sheet antiparallel structure, leads to its precipitation in saturated solutions of Ca/P = 1.67 and induces the formation of parallel large fibrils (0.6 - 1.5 µm). P₁₁-4 organized the HAP nucleation by reducing both the growth rate and size variability of nanocrystals, analyzed by the F test (p < 0.0001, N = 30). P₁₁-4 interacts (K_D = 0.75 ± 0.06 μM) with the KGHRGFSGL motif present at the C-terminal collagen telopeptide domain. P₁₁-4 also increased the amount of HAP and collagen in the MDPC-23 cells.

The presented data propose a mechanism that will help future clinical and/or basic research to better understand a molecule able to inhibit structural collagen loss and help the impaired tissue to remineralize.