Electrostatic interactions lead to the formation of asymmetric collagen-phosphophoryn aggregates
Electrostatic interactions lead to the formation of asymmetric collagen-phosphophoryn aggregates
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DOI：
10.1080/03008200390181672
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发表时间：
2003-01-01
影响因子：
2.9
通讯作者：
Veis, A
中科院分区：
文献类型：
--
作者：
Dahl, T;Veis, A
在骨和牙本质中，细胞外基质结构的形成和矿化是高度依赖于分子间相互作用的复杂过程。在牙本质中，磷酸化蛋白（PP）和I型胶原（COL 1）是参与矿化的主要成分。因此，作为理解组织结构的第一步，我们已经开始研究它们作为pH值、离子强度和相对浓度或混合比的函数的相互作用。通过动态光散射检测聚集体形成和通过旋转阴影电子显微镜（EM）确定聚集体形状来分析复合物形成。EM数据表明，在所研究的pH值下，PP-COLI相互作用导致形成大的原纤聚集体，其中PP沿着原纤表面存在。定量相分布数据表明，在最大聚集点处的摩尔当量为1/1，而不是在静电PP-COL 1当量处。随着离子强度的提高，PP-COL 1聚集体变得更小，但结合和不对称的纤维状聚集体持续存在。在EM中，PP表现为致密的球体。沿着胶原聚集体的表面，PP更大且更开放或延伸，表明COL 1结合的PP可能经历构象变化，开放使得单个PP分子可能与几个COL 1分子相互作用并静电连接。这可能对牙本质结构、稳定性和矿化具有重要意义。
In bone and dentin the formation and mineralization of the extra cellular matrix structure is a complex process highly dependent on intermolecular interactions. In dentin, the phosphophoryns (PP) and type I collagen (COL1) are the major constituents implicated in mineralization. Thus, as a first step in understanding the tissue organization, we have initiated a study of their interaction as a function of pH, ionic strength, and relative concentrations or mixing ratios. Complex formation has been analyzed by dynamic light scattering to detect aggregate formation and by rotary shadowing electron microscopy (EM) to determine aggregate shape. The EM data showed that at the pH values studied, the PP-COLI interaction leads to the formation of large fibrillar aggregates in which the PP are present along the fibril surfaces. The quantitative phase distribution data showed a 1/1molar equivalence at the maximum aggregation point, not at electrostatic PP-COL1 equivalence. As the ionic strength was raised, the PP-COL1 aggregates became smaller but the binding and asymmetric fibrillar aggregation persisted. In EM, the PP appear as dense spheres. Along the surfaces of the collagen aggregates, the PP are larger and more open or extended, suggesting that COL1-bound PP may undergo a conformational change, opening up so that a single PP molecule might interact with and electrostatically link several COL1 molecules. This might have important implications for dentin structure, stability, and mineralization.