Solid state deuterium NMR study of LKα14 peptide aggregation in biosilica
Solid state deuterium NMR study of LKα14 peptide aggregation in biosilica
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DOI：
10.1116/1.4986907
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发表时间：
2017-06-01
期刊：
影响因子：
2.1
通讯作者：
Drobny, Gary P.
中科院分区：
文献类型：
--
作者：
Ferreira, Helen E.;Drobny, Gary P.
在自然界中，包括硅藻、放射虫和海绵在内的生物体使用蛋白质、长链多胺和其他有机分子来调节复杂的硅基结构的组装。在这里，作者研究了小肽的结构特征，旨在模拟在自然系统中发现的较大蛋白质的硅化活性。LKα14(Ac-LKKLKLLKKKLLKL-C)是一种两亲性赖氨酸/亮氨酸重复序列多肽，在极性/非极界面具有α-螺旋二级结构，与二氧化硅共沉淀形成纳米球。以前的C-13魔角旋转研究表明，已知的LKα14在溶液中形成的四聚肽束可能以硅络合物的形式存在，也可能作为二氧化硅形成的催化剂和模板。为了进一步研究LKα14在SiO_2中的聚集，我们用氚固体核磁共振(H-2ss核磁共振)研究了从水溶液、磷酸盐缓冲溶液和SiO_2沉淀状态分离的固体LKα_(14)肽中亮氨酸侧链动力学的不同。模拟H-2单链核磁共振谱线形状，探讨了多肽预聚和硅胶共沉淀的机理。由此得到的核磁共振数据表明，硅胶中的肽束保留了它们在水合固体状态下表现出的疏水内部。然而，核磁共振数据也表明硅胶中的亮氨酸残基可以自由移动，这种情况可能是由于表面赖氨酸侧链与周围的硅胶基质之间的相互作用导致聚集体的结构变形造成的。(三)2017美国真空学会。
In nature, organisms including diatoms, radiolaria, and marine sponges use proteins, long chain polyamines, and other organic molecules to regulate the assembly of complex silica-based structures. Here, the authors investigate structural features of small peptides, designed to mimic the silicifying activities of larger proteins found in natural systems. LK alpha 14 (Ac-LKKLLKLLKKLLKL-C), an amphiphilic lysine/leucine repeat peptide with an alpha-helical secondary structure at polar/apolar interfaces, coprecipitates with silica to form nanospheres. Previous C-13 magic angle spinning studies suggest that the tetrameric peptide bundles that LK alpha 14 is known to form in solution may persist in the silica-complexed form, and may also function as catalysts and templates for silica formation. To further investigate LK alpha 14 aggregation in silica, deuterium solid-state nuclear magnetic resonance (H-2 ssNMR) was used to establish how leucine side-chain dynamics differ in solid LK alpha 14 peptides isolated from aqueous solution, from phosphate-buffered solution, and in the silica-precipitated states. Modeling the H-2 ssNMR line shapes probed the mechanisms of peptide preaggregation and silica coprecipitation. The resulting NMR data indicates that the peptide bundles in silica preserve the hydrophobic interior that they display in the hydrated solid state. However, NMR data also indicate free motion of the leucine residues in silica, a condition that may result from structural deformation of the aggregates arising from interactions between the surface lysine side chains and the surrounding silica matrix. (C) 2017 American Vacuum Society.