A solid-state NMR study of the dynamics and interactions of phenylalanine rings in a statherin fragment bound to hydroxyapatite crystals
A solid-state NMR study of the dynamics and interactions of phenylalanine rings in a statherin fragment bound to hydroxyapatite crystals
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DOI：
10.1021/ja056731m
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发表时间：
2006-04-26
影响因子：
15
通讯作者：
Drobny, GP
中科院分区：
文献类型：
--
作者：
Gibson, JM;Popham, JM;Drobny, GP
细胞外基质蛋白通过作为细胞的粘附位点、触发细胞信号通路以及直接调节羟基磷灰石（骨骼和牙齿的矿物成分）的初级和/或次级结晶来调节硬组织的生长。尽管这些蛋白质在人类硬组织生长的调节中起着关键作用，但这些蛋白质识别矿物表面的确切机制尚不清楚。矿物表面和蛋白质之间的相互作用很可能涉及晶格和蛋白质侧链之间的特定接触，因此阐明蛋白质侧链与其相应的无机矿物表面之间相互作用的性质将为硬组织生长的识别和调节提供见解。各向同性化学位移、化学位移各向异性（csa）、核磁共振线宽信息、C-13旋转框架弛豫测量以及用REDOR核磁共振直接检测蛋白质侧链上C-13自旋与晶体表面P-31自旋之间的相关性表明，在唾液甾体蛋白n端15个氨基酸衍生的肽片段（即SN-15）中，靠近肽c端（F14）的苯丙氨酸侧链受到动态约束，并在靠近肽表面的地方定向，而靠近肽n端（F7）的苯丙氨酸侧链更具流动性，并在远离羟基磷灰石表面的地方定向。利用F7和F14的相对动力学和与表面的接近度，以及SN-15独特赖氨酸侧链（即K6）的先前数据，构建了表面结合肽的结构及其与晶体表面的取向的新图像。
Extracellular matrix proteins regulate hard tissue growth by acting as adhesion sites for cells, by triggering cell signaling pathways, and by directly regulating the primary and/or secondary crystallization of hydroxyapatite, the mineral component of bone and teeth. Despite the key role that these proteins play in the regulation of hard tissue growth in humans, the exact mechanism used by these proteins to recognize mineral surfaces is poorly understood. Interactions between mineral surfaces and proteins very likely involve specific contacts between the lattice and the protein side chains, so elucidation of the nature of interactions between protein side chains and their corresponding inorganic mineral surfaces will provide insight into the recognition and regulation of hard tissue growth. Isotropic chemical shifts, chemical shift anisotropies (CSAs), NMR line-width information, C-13 rotating frame relaxation measurements, as well as direct detection of correlations between C-13 spins on protein side chains and P-31 spins in the crystal surface with REDOR NMR show that, in the peptide fragment derived from the N-terminal 15 amino acids of salivary statherin (i.e., SN-15), the side chain of the phenylalanine nearest the C-terminus of the peptide (F14) is dynamically constrained and oriented near the surface, whereas the side chain of the phenylalanine located nearest to the peptide's N-terminus (F7) is more mobile and is oriented away from the hydroxyapatite surface. The relative dynamics and proximities of F7 and F14 to the surface together with prior data obtained for the side chain of SN-15's unique lysine (i.e., K6) were used to construct a new picture for the structure of the surface-bound peptide and its orientation to the crystal surface.