Shapes of Biomacromolecular Complexes by Solid-State NuclearMagnetic Resonance

9604860 Schaefer这项工作的目标是通过固体核磁共振对构成超分子结构或组装的蛋白质和脱氧核糖核酸进行表征。这些包括昆虫角质层、海洋生物和植物细胞壁中的交联蛋白，以及稳定的冻融保护剂基质中包裹的蛋白质，以及由树枝状大分子紧凑的DNA。稳定同位素标记物之间的偶极耦合将通过REDOR(旋转-回波双共振)和REDOR类核磁共振重新耦合实验在这些复杂的生物大分子组件中直接测量。在有关昆虫、贻贝和植物蛋白质的工作中，将回答有关这些结构是如何交联和稳定的具体化学问题。将寻找稳定缓冲糖杯中脆弱蛋白质复合体的新方法。然后，这些基质将被用来检测被困在玻璃中的烯丙酮基莽草酸3-磷酸合成酶的自然-底物反应中间体。最后，通过将稳定的自由基埋入两亲性粒子的核心，使蛋白质络合并压缩DNA，将创建一种掺杂剂，用于动态核极化实验。REDOR将被用来表征局部结构，由此产生的距离将被用作分子动力学模拟的约束，旨在可视化复合体的整体形状。许多生化和生物物理过程是由分子超结构或在分子超结构中进行的。这些超结构是没有原子级结构信息的大分子络合物或聚集体，因为它们不是可溶的(无溶液核磁共振)，也不结晶(无X射线结晶学)。这项工作将为重要的实际问题(虫害管理、船体藤壶污垢、酶反应途径、DNA紧凑)提供具体的见解，并产生一种新的具有原子级分辨率的生物物理结构工具(固态核磁共振)，可以应用于其他难以处理的系统。

9604860 Schaefer The goal of the work is the characterization by solid-state NMR of proteins and DNA that are part of a supramolecular structure or assembly. These include cross-linked proteins in insect cuticle, marine organisms and plant cell walls, as well as proteins encapsulated in stabilizing lyoprotectant matrices, and DNA compacted by dendrimer-like macromolecules. Dipolar couplings between stable-isotope labels will be measured directly in these complicated biomacromolecular assemblies by REDOR (Rotational-echo double resonance) and REDOR-like NMR recoupling experiments. In the work on insect, mussel, and plant proteins, specific chemical questions will be answered as to how these structures are cross-linked and stabilized. A search will be made for new ways to stabilize fragile protein complexes in a buffered sugar glass. These matrices will then be used to examine the natural-substrate reaction intermediates of enolpyruvylshikimate 3-phosphate synthase which have been trapped in the glass. Finally, a dopant will be created for dynamic nuclear polariation experiments by burying a stable free radical in the core of an amphiphilic particle that complexes proteins and compacts DNA. REDOR will be used to characterize the local structure and the resulting distances will be used as constraints in molecular dynamics simulations designed to visualize the overall shapes of the complexes. Many biochemical and biophysical processes are carried out by or in molecular superstructures. These superstructures are macromolecular complexes or aggregates for which there is no atomic-level structural information because they are not soluble (no solution NMR) and don't crystalize (no x-ray crystallography). This work will provide specific insights into important practical problems (insect pest management, barnacle fouling of ship hulls, enzyme reaction pathways, DNA compaction) and generate a new kind of biophysical structural tool with atomic-level resolution (solid-state NMR) that is applic able to otherwise intractable systems.