Tao Jinhui, Fijneman Andreas, Wan Jiaqi, Prajapati Saumya, Mukherjee Kaushik, Fernandez-Martinez Alejandro, Moradian-Oldak Janet, De Yoreo James J
Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States.
Laboratory of Materials and Interface Chemistry and Center of Multiscale Electron Microscopy, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
Cryst Growth Des. 2018 Dec 5;18(12):7391-7400. doi: 10.1021/acs.cgd.8b01066. Epub 2018 Oct 22.
Although amelogenin comprises the vast majority of the matrix that templates calcium phosphate nucleation during enamel formation, other proteins, particularly enamelin, are also known to play an important role in the formation of enamel's intricate architecture. However, there is little understanding of the interplay between amelogenin and enamelin in controlling processes of mineral nucleation and growth. Here, we used an model to investigate the impact of enamelin interaction with amelogenin on calcium phosphate nucleation for a range of enamelin-to-amelogenin ratios. We found that amelogenin alone is a weak promoter of nucleation, but addition of enamelin enhanced nucleation rates in a highly nonlinear, nonmonotonic manner reaching a sharp maximum at a ratio of 1:50 enamelin/amelogenin. We provide a phenomenological model to explain this effect that assumes only isolated enamelin proteins can act as sites of enhanced nucleation, while enamelin oligomers cannot. Even when interaction is random, the model reproduces the observed behavior, suggesting a simple means to tightly control the timing and extent of nucleation and phase transformation by amelogenin and enamelin.
尽管釉原蛋白在釉质形成过程中构成了模板化磷酸钙成核的绝大部分基质，但其他蛋白质，尤其是釉蛋白，也被认为在釉质复杂结构的形成中发挥着重要作用。然而，对于釉原蛋白和釉蛋白在控制矿物成核和生长过程中的相互作用，人们了解甚少。在此，我们使用一个模型来研究在一系列釉蛋白与釉原蛋白比例下，釉蛋白与釉原蛋白相互作用对磷酸钙成核的影响。我们发现，单独的釉原蛋白是一种较弱的成核促进剂，但添加釉蛋白会以高度非线性、非单调的方式提高成核速率，在釉蛋白/釉原蛋白比例为1:50时达到急剧最大值。我们提供了一个现象学模型来解释这种效应，该模型假设只有孤立的釉蛋白分子才能作为增强成核的位点，而釉蛋白寡聚体则不能。即使相互作用是随机的，该模型也能重现观察到的行为，这表明存在一种简单的方式来严格控制釉原蛋白和釉蛋白成核及相变的时间和程度。
