SYNCHROTRON X-RAY STUDIES OF BIOMOLECULAR MATERIALS

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 拟议的实验的目的是阐明的结构和相互作用的性质，在重组组件的丝状神经丝（NF）来自牛中枢神经系统的神经元。NF在神经元中形成网络，其被认为在神经元过程（轴突和树突）的结构稳定性和作为分散在整个过程的细胞骨架中的微管的支架两者中起关键作用。神经丝由三种均聚物NF-L、NF-M和NF-H组成，以不同的组成组装以形成具有突出的C末端侧臂的成熟NF丝。然而，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。在成熟的神经元中，三种NF组分的组成在一个狭窄的范围内受到调节，组成的偏差导致NF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（例如肌萎缩性侧索硬化症，Lou Gehrig？的疾病）。因此，重要的是要了解不同的侧臂在通过侧臂-侧臂相互作用赋予网络稳定性方面的作用。我们最近的同步加速器SAXS数据表明，与NF-M或NF-H组成的侧臂的丝间相互作用的性质不同的行为。使用同步加速器SAXS-渗透压技术，提出了一系列的直接力测量，这与互补相行为的研究相结合时，应导致全面了解神经丝之间的相互作用的性质。将在NF凝胶中进行研究，作为模拟体内条件的二元（NF-LH、NF-LM）和三元（NF-LMH）混合物中侧臂密度的函数。除了进一步增强我们对带电生物聚合物网络的了解外，这些实验还应该增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. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. 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.