Effects of Noncollagenous Proteins on Collagen Calcification.

本文研究了在三种不同条件下，即由β-甘油磷酸钙和碱性磷酸酶组成的钙化液、由无机钙和磷酸盐组成的钙化液和允许钙和磷通过扩散相遇的琼脂糖凝胶三种不同条件下，非胶原蛋白骨结素、骨GLA蛋白和牙本质磷蛋白对磷灰石形成的影响。在所有条件下，不含任何非胶原蛋白的胶原蛋白对磷灰石的形成没有积极的、必要的影响，这表明胶原本身并不促进体外钙化。非胶原蛋白在溶液中以游离形式存在时，会减缓磷灰石的形成和随后的晶体生长。在非胶原蛋白存在下形成的磷灰石晶体尺寸变小，在形态上与骨和牙本质相似。这一发现可能表明溶液中的非胶原蛋白在体内对磷灰石晶体的生长起着重要的调节作用。在凝胶中运动受限的非胶原蛋白中，牙本质磷蛋白和磷高磷蛋白在一维双扩散体系中以相对较低的钙和磷浓度引发钙化时，发现它们促进了钙化。在三种不同实验条件下获得的数据清楚地表明，非胶原蛋白的状态，即存在于溶液中的游离态或存在于其运动受限的状态，是阐明它们在体内钙化中所起作用的关键。

Effects of noncollagenous proteins of osteonectin, bone Gla protein and dentin phosphoprotein on formation of apatite were studied under three different conditions, i. e., calcifing solutions consisting of beta -glycerophosphate calcium and an alkaline phophatase enzyme, calcifing solutions consisting of inorganic calcium and phosphate, and agarose gel, in which calcium and phosphate were allowed to meet each other by diffusion. Under every condition collagen without any noncollagenous protein was found to excerpt no positive, essential effect on the formation of apatite, suggesting that collagen itself does not promote in vitro calcification. Noncollagenous proteins, when present free in solution, retarded the formation of apatite and the subsequent crystal growth as well. Apatite formed in the presence of noncollagenous proteins became smaller in crystal size, resembling that of bone and dentin in morphology. This finding may indicate that the noncollagenous proteins present free in solution play some important role in regulating crystal growth of apatite in vivo.Of the nocollagenous proteins with their movement restricted in gel, dentin phosphoprotein and phosvitin were found to promote calcification, when relatively lower concentration of calcium and phosphate was used to initiate calcification in the one-dimensional double diffusion system. The data obtained under the three different experimental conditions clearly suggest that state of noncollagenous proteins, i. e., present free in solution or present with their movement restricted, is a key point to elucidate their roles playing in in vivo calcification.