Calcium-specific precipitation of dentin phosphoprotein: a new method of purification and the significance for the mechanism of calcification.

Calcium, but not magnesium or strontium ions, specifically induce the precipitation of dentin phosphoprotein, which is reversibly solubilized by EDTA. This finding is very useful in pruifying dentin phosphoprotein of either a free or matrix-bound type. Bovine dentin phosphoproteins, thus isolated, contain a minimal amount of contaminant protein, unlike previous preparations.