Atomistic simulation study of calcium, phosphate and fluoride ion association to the teleopeptide-tails of collagen - Initial steps to biomineral formation

The attachment of single ions to putative adsorption sites in the tails of collagen fibers is investigated by means of molecular dynamics simulations and discussed with respect to the very early steps of apatite/collagen biamineral formation. Our studies clearly demonstrate an increased flexibility of the tails of the triple-helical collagen protein. Apart from the termini of the backbone, several side chains were also observed to be freely accessible to ion attachment from aqueous solution. The teleopeptide was systematically scanned for suitable adsorption sites for calcium, phosphate and fluoride ions. Association of these ions was then explored from potential of mean force calculations. The resulting energy profiles reveal a variety of favorable protein-ion bonds and hint at the suitability of the collagen tails to promote apatite aggregation.