The interaction of bovine dentine phosphophoryn and collagen during fibrillogenesis of collagen in vitro.

Bovine dentinal phosphophoryn retards the rate of collagen self-assembly when monomeric collagen is the kinetic unit in fibrillogenesis in vitro. This inhibition is dependent on phosphorylation of the protein and affects the lag period rather than the growth phase for the formation of collagen fibrils. Treatment of the phosphophoryn with calcium markedly increases the inhibitory effect. The use of several fluorescent hydrophobic probes indicates that the calcium-binding to phosphophoryn does not expose any additional interacting hydrophobic domains, thus suggesting that calcium potentiates this interaction, probably by providing a different spatial arrangement of charged groups on this polyelectrolyte, phosphophoryn.