Cantilever Magnetic Resonance of Biomolecules

描述（申请人提供）：迫切需要新的工具来确定单个大分子和大分子复合物的三维结构。这个R01更新应用程序的目标是创建一个“分子显微镜”，能够成像质子密度，或绘制电子自旋标签的位置，一个蛋白质或大分子复合体的单一拷贝。我们将开发一种能够扫描探针核磁共振成像和电子自旋共振成像的分子显微镜。仪器的开发将直接用于研究与脂质双分子层结合或位于细胞膜上的天然和自旋标记的大分子复合物。我们的具体目标是：(1)利用磁尖悬臂梁和磁共振力梯度检测来观察单个氮氧化物标记蛋白质副本的电子自旋共振（ESR）和生物分子中数百个质子的核磁共振（NMR）；(2)了解和减轻（通过样品制备，悬臂设计和自旋调制方案）在低温下真空表面附近的超灵敏悬臂所经历的多余力和力梯度噪声，并学习通过在磁共振力显微镜中提供更完美的自旋翻转来延长自旋相干时间；(3)发展时域傅里叶图像编码，提高扫描探针磁共振成像速度。

DESCRIPTION (provided by applicant): New tools for determining the three dimensional structure of single macromolecules and macromolecular complexes are urgently needed. The goal of this R01 renewal application 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. PUBLIC HEALTH RELEVANCE: New tools for determining the three dimensional structure of single macromolecules and macromolecular complexes are urgently needed. We are developing a "molecular microscope" to image nanoscale entities of relevance to biomedicine. Such an instrument would dramatically impact a broad spectrum of biological processes, disorders, and diseases.