Institute for Biomedical Engineering, Biointerface Group, RWTH Aachen University, D-52074 Aachen, Germany.
Biointerphases. 2007 Mar;2(1):16-20. doi: 10.1116/1.2714924.
The concentration of mineral solutes in mammalian blood is considerably higher than that predicted by their solubility product. The plasma protein fetuin-A inhibits calcium phosphate deposition by forming colloidal calciprotein particles (CPPs). In this article the authors present a detailed small angle neutron scattering study including contrast variation analysis providing detailed quantitative information on the three-dimensional topology of the CPPs and on their morphogenesis. In detail the authors found the following: (i) A two stage growth process showing spontaneously formed primary particles with a size of about 500 A diameter that subsequently transformed to 1000 A sized particles which were stable for at least 24 h. (ii) A particular shielding topology was observed for the second CPP state, namely, that a densely packed fetuin-A monolayer covers a mineral core and thereby prevents further crystal growth. (iii) Transmission electron microscopy analysis of in vitro synthesized second state CPPs revealed striking similarities to material retrieved from a human peritonitis patient. This latter finding underscores the importance of short- and long-term stabilizations of CPPs by fetuin-A to enable clearing of mineral debris in the body.
哺乳动物血液中的矿物质溶质浓度远远高于其溶解度积所预测的浓度。血浆蛋白胎球蛋白 A 通过形成胶体磷酸钙颗粒 (CPPs) 来抑制磷酸钙沉积。在本文中，作者进行了详细的小角度中子散射研究，包括对比变化分析，提供了 CPPs 的三维拓扑结构和形态发生的详细定量信息。具体而言，作者发现：(i) 存在一个两阶段生长过程，其中包括自发形成的约 500 Å 直径的初级颗粒，随后转化为 1000 Å 大小的颗粒，这些颗粒至少稳定 24 小时。(ii) 观察到第二 CPP 状态的特定屏蔽拓扑结构，即紧密堆积的胎球蛋白 A 单层覆盖在矿物核心上，从而防止进一步的晶体生长。(iii) 对体外合成的第二 CPP 进行的透射电子显微镜分析显示，与从人类腹膜炎患者中提取的物质具有惊人的相似性。这一发现强调了胎球蛋白 A 对 CPPs 的短期和长期稳定的重要性，以实现体内矿物质碎片的清除。
