Cantilever Magnetic Resonance of Biomolecules

测定单个大分子三维结构的新工具， 迫切需要大分子复合物。此R 01更新提案的目标是 是创造一个“分子显微镜”，能够成像的质子密度，或 映射电子自旋标记的位置，蛋白质的单个拷贝，或 大分子复合物 我们将开发一种能够扫描探针核磁共振的分子显微镜 核磁共振（NMR）成像和电子自旋共振（ESR）成像。仪器 发展方向将是研究天然的和自旋标记的 大分子复合物结合到脂质双层或位于细胞膜中。 我们的具体目标是：（1）开发磁尖杠杆和力梯度 磁共振检测，以观察电子自旋共振（ESR）从一个单一的 复制一个氮氧标记的蛋白质，并观察核磁共振（NMR） 从生物分子中的几百个质子;（2）理解和减轻（通过样品 制备、悬臂梁设计和自旋调制方案）过量的力和力- 真空中表面附近超灵敏度悬臂梁的梯度噪声. 低温，并学习通过给予更多的自旋相干时间来延长自旋相干时间。 完美的自旋翻转在磁共振力显微镜;和（3）开发时间- 域傅立叶图像编码以提高扫描探头磁共振成像速度 共振

New tools for determining the three dimensional structure of single macromolecules and macromolecular complexes are urgently needed. The goal of this R01 renewal proposal is to create a "molecular microscope" capable of imaging the proton density of, or mapping the locations of electron spin labels in, a single copy of a protein or macromolecular complex. We will develop a molecular microscope capable of scanned-probe nuclear magnetic resonance (NMR) imaging and electron spin resonance (ESR) imaging. Instrument development will be directed towards the study of native and spin-labeled macromolecular complexes bound to a lipid bilayer or located in a cell membrane. Our specific aims are: (1) To exploit magnetic-tipped cantilevers and force-gradient detection of magnetic resonance to observe electron spin resonance (ESR) from a single copy of a nitroxide-labeled protein and to observe nuclear magnetic resonance (NMR) from a few hundred protons in a biomolecule; (2) To understand and mitigate (via sample preparation, cantilever design, and spin modulation schemes) excess force and force- gradient noise experienced by ultrasensitive cantilevers near surfaces in vacuum at cryogenic temperatures and to learn to prolong spin coherence time by giving more perfect spin flips in magnetic resonance force microscopy; and (3) To develop time- domain Fourier image encoding to increase the imaging speed of scanned-probe magnetic resonance.