Nature of Bone Mineral: Inception, Maturation, Aging

描述(申请人提供)：生物无机晶体的功能取决于它们的大小、形状、长程和短程有序性、化学成分、特定的离子环境以及与细胞外基质和细胞的空间和化学关系。骨的功能包括对力学特性的贡献，维持细胞外液动态平衡的离子储存库，以及与细胞的相互作用，所有这些都控制着它们的相互作用特性，从而控制它们的机械和生理作用。来自体外31P核磁共振、光谱和成像以及活体动物(最终是人类)实验的数据将提供真实的3-D体积骨矿物和骨基质(胶原)密度，根据这些密度可以非侵入性地计算矿化程度。这一补充信息对评估体内骨组织在许多疾病中的作用具有临床意义，例如骨质疏松症、骨折愈合和儿童遗传疾病。由于骨的生理和力学性能在很大程度上依赖于晶体的结构，特别是形成的初始固相，因此将通过高准直同步产生的广角X射线衍射和同时的X射线荧光(钙浓度)、FTIR成像和显微光谱以及非弹性中子散射来进行原位研究。我们还将从理论和实验上解决预成核态的问题，即通过分子轨道计算首先与有机基质组分结合的钙、磷原子和离子的初始小团簇的化学和结构构象。骨物质是将脆性的钙磷纳米晶掺入到柔软的有机基质中形成的多相复合材料。机械和生理特性还严重依赖于两个主要结构成分和其他有机成分之间的化学和空间关系，这将通过高分辨率同步辐射产生的小角X射线衍射进行研究，为晶体和胶原之间的空间关系以及晶体沉积的胶原纤维内空间的数学建模提供基础。这将伴随着用一种新的原子力显微镜技术确定晶体的三维形状和大小。对磷蛋白和磷酸化位点的分离、纯化和测序的研究将继续进行。长期目标将是制备主要物种的单晶，用于分子结构的结晶学测定。

DESCRIPTION (provided by applicant): Functions of biological inorganic crystals depend on their size, shape, long- and short-range order, chemical composition, specific ion environments, and spatial and chemical relationships with extracellular matrices and cells. Bone functions include contributions to mechanical characteristics, ion reservoir to maintain homeostasis of extra cellular fluids, and interactions with cells, all of which control their interactive properties and thus their mechanical and physiological roles. Data from in vitro 31P NMR, spectroscopy and imaging and in vivo experiments in living animals (eventually humans) will provide true 3-D volumetric bone mineral and bone matrix (collagen) densities from which extent of mineralization can be calculated non-invasively. This additional information has clinical implications for evaluating bone tissue in vivo in many diseases such as osteoporosis, healing of fractures and genetic disorders in children. Because the physiological and mechanical properties of bone are significantly dependent on the structure of the crystals, particularly the initial solid phase formed, studies will be pursued in situ by highly collimated synchrotron-generated wide-angle x-ray diffraction and simultaneous x-ray fluorescence (Ca concentration), FTIR imaging and microspectroscopy, and inelastic neutron scattering. We will also address the problem both theoretically and experimentally of the pre-nucleation states, viz., the chemical and structural conformation of the initial small clusters of Ca and P atoms and ions that are first bound to organic matrix constituents using molecular orbital calculations. Bone substance is a multiphase composite formed by the incorporation of brittle Ca-P nanocrystals into a soft organic matrix. Mechanical and physiological properties are also profoundly dependent on chemical and spatial relationships between the two major structural and other organic components, which will be studied by high-resolution synchrotron-generated low-angle x-ray diffraction providing the basis for mathematical modeling of spatial relationships between crystals and collagen and the spaces within the collagen fibril where the crystals are deposited. This will be accompanied -by the determination of the 3-dimensional shape and size of the crystals, determined by a new atomic force microscopy technique. Studies will continue on isolation, purification, and sequencing of phosphoproteins and sites of phosphorylation. Long-range goal wilt be preparation of single crystals of major species for crystallographic determination of molecular structure.