Lee S L, Glimcher M J
Calcif Tissue Int. 1981;33(4):385-94. doi: 10.1007/BF02409461.
Fractionation of the EDTA-soluble, noncollagenous proteins of the organic matrix of chicken bone by Sephadex G-100 molecular sieving has revealed that the majority of the organic phosphorus is present in two fractions, from one of which a homogeneous phosphoprotein has been isolated. The purified phosphoprotein has an apparent molecular weight of 12,000 and contains both O-phosphoserine and O-phosphothreonine. 31P-NMR spectroscopy demonstrates that all of the organic phosphorus exists in the form of phosphomonoesters which have an average pK2 of 6.8. The phosphoprotein is highly acidic due to its high content of dicarboxylic acids in addition to the presence of organic phosphorus. The characteristic amino acid composition of the phosphoprotein establishes its noncollagenous nature and highlights the differences among bone, dentin, and enamel phosphoproteins. The absence of gamma-carboxyglutamic acid distinguishes it from osteocalcin, the noncollagenous gamma-carboxyglutamic acid-containing peptide of bone matrix.
通过葡聚糖G - 100分子筛对鸡骨有机基质中可溶于乙二胺四乙酸（EDTA）的非胶原蛋白进行分级分离，结果表明大部分有机磷存在于两个组分中，其中一个组分已分离出一种均一的磷蛋白。纯化后的磷蛋白表观分子量为12,000，含有O - 磷酸丝氨酸和O - 磷酸苏氨酸。磷-31核磁共振光谱表明，所有有机磷均以磷酸单酯的形式存在，其平均pK2为6.8。除了含有有机磷外，该磷蛋白因富含二羧酸而呈高酸性。磷蛋白独特的氨基酸组成确定了其非胶原蛋白的性质，并突出了骨、牙本质和牙釉质磷蛋白之间的差异。缺乏γ-羧基谷氨酸使其区别于骨钙素，即骨基质中含γ-羧基谷氨酸的非胶原蛋白肽。
