SYNCHROTRON X-RAY STUDIES OF BIOMOLECULAR MATERIALS

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 拟议的实验旨在阐明牛中枢神经系统神经元来源的细丝神经丝(NFs)重组组件的结构和相互作用的性质。神经纤维在神经元中形成网络，被认为在神经元突起(轴突和树突)的结构稳定性以及作为分散在突起细胞骨架中的微管的支架中发挥关键作用。神经丝由三种均聚体NF-L、NF-M和NF-H组成，它们以不同的组成组装在一起，形成具有突出C端侧臂的成熟NF丝。然而，细丝间相互作用的性质和网络中每个均聚物的确切作用仍不清楚。在成熟神经元中，三种核因子组分的组成在一个很小的范围内被调节，组成上的偏差会导致核因子网络的破坏(假设是由于不正确的侧臂相互作用)和运动神经元疾病(例如肌萎缩侧索硬化症、卢·格里克？S病)。因此，重要的是要了解不同的侧武器在通过侧武器相互作用为网络提供稳定性方面所起的作用。我们最近的同步加速器SAXS数据表明，与由NF-M或NF-H组成的侧武器之间的细丝间相互作用具有本质上的不同行为。利用同步加速器SAXS-渗透压技术，提出了一系列的直接力测量方法，与互补的相行为研究相结合，将导致对神经细丝之间相互作用的本质的全面理解。这些研究将在核因子凝胶中进行，作为二元(核因子-1H、核因子-1M)和三元(核因子-LMH)混合物中侧武器密度的函数，模拟体内条件。除了进一步加强我们对带电生物聚合物网络的了解外，这些实验还应该加强对轴突细胞骨架内结构和相互作用的理解。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The proposed experiments aim to elucidate the nature of structures and interactions in reconstituted assemblies of filamentous neurofilaments (NFs) derived from neurons of the bovine central nervous system. NFs form networks in neurons, which are believed to play a key role both in the structural stability of neuronal processes (axons and dendrites) and as scaffolds for microtubules dispersed throughout the cytoskeleton of the processes. Neurofilaments consist of three homopolymers NF-L, NF-M, and NF-H, assembled in varying composition to form the mature NF filament with protruding C-terminus sidearms. However, the nature of the interfilament interactions and the precise role of each homopolymer within the network remain unclear. In mature neurons the composition of the three NF fractions is regulated over a narrow range with deviations in composition resulting in the disruption of the NF-network (hypothesized to be due to incorrect sidearm interactions) and motor neuron diseases (e.g. amyotrophic lateral sclerosis, Lou Gehrig?s disease). Thus, it is important to understand the role of distinct sidearms in imparting stability to the network through sidearm-sidearm interactions. Our recent synchrotron SAXS data suggests qualitatively different behavior for interfilament interactions with sidearms consisting of either NF-M or NF-H. Using the synchrotron SAXS-osmotic pressure technique, a series of direct force measurements are proposed, which when combined with complementary phase behavior studies, should result in a comprehensive understanding of the nature of the interactions between neurofilaments. The studies will be conducted in NF gels as a function of sidearm densities in binary (NF-LH, NF-LM), and ternary (NF-LMH) mixtures mimicking in-vivo conditions. Aside from further enhancing our knowledge of charged biopolymer networks, the experiments should enhance the understanding of structures and interactions within the axonal cytoskeleton.