[Potential role of phosphoprotein in collagen mineralization--an experimental study in vitro]

To examine the potential role of phosphoprotein in collagen mineralization, a series of experiments were carried out in vitro using native type collagen fibrils containing phosphoprotein. Ten different preparations of decalcified chicken bone were used for nucleation experiments, employing experimentally established metastable solutions of 10 mg/100 ml, ionic strength 0.165, at 25 degrees C. The specimens were analysed at regular intervals for their calcium and phosphorus content. Amino acid analyses including quantitation of phosphoserine and phosphothreonine were performed on all the samples. The time lag between the incubation of the sample in the metastable solution and the initiation of nucleation was found to be directly related to the concentration of the phosphoaminoacids. The data suggest that phosphoprotein has an effect on the speed of the collagen mineralization, thus playing a significant role in initiation of the tissue calcification.