STRUCTURAL AND ELEMENTAL ANALYSIS OF MACROMOLECULAR ASSEMBLIES

这个项目的目标是表征形状，分子量 单个大分子的分布和元素组成， 大分子组装，重点是组件的 细胞骨架 这个项目依赖于我们独特的场致发射 扫描透射电子显微镜（STEM），配备用于 蛋白质分子量分布的暗场质量图 nm分辨率，并通过电子能量损失进行分析和绘图 （EELS）光谱的分布生理上重要的 元素，如P，Ca和S，分辨率<10 nm。 的应用 该技术通过测定 鱿鱼个体轴突的磷酸化和亚基组织 神经丝;最近对这些数据的改进揭示了一种新的 由八个螺旋线圈组成的中间丝的结构 每个横截面含有异二聚体，每个具有一条重链和一条轻链。 重链携带至少40个磷酸基团。 这项工作， 需要0.5个P原子/nm的灵敏度，代表第一个 “纳米分析”的生物学应用。

The goal of this project is to characterize the shape, molecular weight distribution and elemental composition of individual macromolecules and macromolecular assemblies, with emphasis on components of the cytoskeleton. This project depends on our unique field-emission scanning transmission electron microscope (STEM), which is equipped for dark-field mass mapping of protein molecular weight distributions at 2 nm resolution and for analyzing and mapping by electron energy loss (EELS) spectroscopy the distribution of physiologically important elements such as P, Ca and S at a resolution of <10 nm. Application of this technology is well illustrated by the determination of the phosphorylation and subunit organization of individual squid axonal neurofilaments; recent refinement of these data have revealed a novel structure for intermediate filaments, consisting of eight coiled-coil heterodimers per cross section, each with one heavy and one light chain. The heavy chain carries at least 40 phosphate groups. This work, requiring a sensitivity of 0.5 P atoms/nm, represents the first biological application of "nanoanalysis".