Molecular modeling and mechanics studies on the initial stage of the collagen-mineralization process

A molecular modeling and mechanics method was employed to study the initial stage of the collagen-mineralization process. Collagen was modeled as a collagen-like peptide CH3CO-(Gly-Pro-Pro)10-NHCH3. Calcium ions were placed at a certain distance from specified C=O groups. Molecular mechanics simulations were then carried out to find the optimized structures. Calculation results showed that the calcium ions were attracted to an equilibrium position by the collagen-like peptide. The binding energies for the first, second, and third attracted calcium ion are 145.7 kCal/mol, 69.8 kCal/mol, and 47.1 kCal/mol, respectively. When more than one calcium ion was placed, the special spatial structure of the collagen-like peptide could arrange the attracted calcium ions. Simulation results for three calcium ions showed that the final structure was similar to that in HA crystal.