Department of Chemistry , University of Washington , Box 351700, Seattle , Washington 98195 , United States.
Department of Chemical Engineering , University of Washington , Seattle , Washington 98195 , United States.
J Am Chem Soc. 2019 Feb 6;141(5):1998-2011. doi: 10.1021/jacs.8b10990. Epub 2019 Jan 24.
Elucidation of the structure and interactions of proteins at native mineral interfaces is key to understanding how biological systems regulate the formation of hard tissue structures. In addition, understanding how these same proteins interact with non-native mineral surfaces has important implications for the design of medical and dental implants, chromatographic supports, diagnostic tools, and a host of other applications. Here, we combine solid-state NMR spectroscopy, isotherm measurements, and molecular dynamics simulations to study how SNa15, a peptide derived from the hydroxyapatite (HAP) recognition domain of the biomineralization protein statherin, interacts with HAP, silica (SiO), and titania (TiO) mineral surfaces. Adsorption isotherms are used to characterize the binding affinity of SNa15 to HAP, SiO, and TiO. We also apply 1D C CP MAS, 1D N CP MAS, and 2D C-C DARR experiments to SNa15 samples with uniformly C- and N-enriched residues to determine backbone and side-chain chemical shifts. Different computational tools, namely TALOS-N and molecular dynamics simulations, are used to deduce secondary structure from backbone and side-chain chemical shift data. Our results show that SNa15 adopts an α-helical conformation when adsorbed to HAP and TiO, but the helix largely unravels upon adsorption to SiO. Interactions with HAP are mediated in general by acidic and some basic amino acids, although the specific amino acids involved in direct surface interaction vary with surface. The integrated experimental and computational approach used in this study is able to provide high-resolution insights into adsorption of proteins on interfaces.
阐明蛋白质在天然矿物界面的结构和相互作用是理解生物系统如何调节硬组织结构形成的关键。此外，了解这些相同的蛋白质如何与非天然矿物表面相互作用对于设计医疗和牙科植入物、色谱支持物、诊断工具以及许多其他应用具有重要意义。在这里，我们结合固态 NMR 光谱、等温测量和分子动力学模拟来研究 SNa15（一种源自生物矿化蛋白 statherin 的羟磷灰石（HAP）识别域的肽）如何与 HAP、二氧化硅（SiO）和二氧化钛（TiO）矿物表面相互作用。吸附等温线用于表征 SNa15 与 HAP、SiO 和 TiO 的结合亲和力。我们还应用 1D C CP MAS、1D N CP MAS 和 2D C-C DARR 实验对均 C 和 N 富集残基的 SNa15 样品进行了研究，以确定主链和侧链化学位移。不同的计算工具，即 TALOS-N 和分子动力学模拟，用于从主链和侧链化学位移数据中推断二级结构。我们的结果表明，SNa15 在吸附到 HAP 和 TiO 时采用α-螺旋构象，但在吸附到 SiO 时螺旋结构大部分解开。与 HAP 的相互作用通常由酸性和一些碱性氨基酸介导，尽管与表面直接相互作用的特定氨基酸因表面而异。本研究中使用的综合实验和计算方法能够提供关于蛋白质在界面上吸附的高分辨率见解。
