Overhauser Dynamic Nuclear Polarization at high magnetic fields (9.4 T) on Lipid Bilayers

脂质双层上高磁场 (9.4 T) 下的 Overhauser 动态核极化

• 批准号: 405972957
• 负责人: Professor Dr. Thomas F. Prisner
• 金额: --
• 依托单位: Institut für Physikalische und Theoretische Chemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/405972957?language=en
• 关键词: Overhauser; Dynamic; Nuclear; Polarization; magnetic

The prolongation of this project aims to establish a quantitative link between the OE-DNP experi-ments with lipid bilayers containing spin-labeled lipids measured in the first period of this project, and the underlying molecular motions that give rise to these experimental results. While the re-ported DNP and cw-EPR experiments provide valuable hints about the nature and dynamics of the local environments surrounding the spin labels, interpreting the experiments in terms of the mo-tions of the lipids and the water molecules is difficult. To provide such an interpretation, we will perform atomistic molecular dynamics (MD) simulations of several lipid-bilayer systems with em-bedded spin-labeled lipids. The MD trajectories will be subjected to two types of quantitative anal-yses that will allow for direct comparison with the reported experiments. First, the dynamics of the spin labels from the simulations will be used to calculate multi-frequency cw-EPR spectra. Second, the dynamics of the vector pointing from an electron spin to a proton spin will be used to calculate the spectral density function of the dipolar interaction between the spins, from which an OE-DNP coupling factor will be obtained. An eventual agreement between the calculations and the experi-ments will shed light on the molecular factors on which the high-field OE-DNP enhancements rely. A possible disagreement between the experiments and the calculations, on the other hand, will illuminate latent deficiencies in the MD simulations. Additionally, we want to extend our 1H Over-hauser DNP experiments on lipid bilayers to DOPC lipids. This will allow exploring if the length mismatch between the spin-labeled lipids with the formerly studied DMPC lipids could be respon-sible for the experimental observed low position dependence of the DNP efficiency by causing structural disorder or changing the accessibility and dynamics of internal water molecules.

本项目的延长旨在建立OE-DNP实验与本项目第一阶段测量的含有自旋标记脂质的脂质双层之间的定量联系，以及引起这些实验结果的潜在分子运动。虽然报道的DNP和cw-EPR实验提供了关于自旋标记周围局部环境的性质和动力学的有价值的提示，但根据脂质和水分子的运动来解释实验是困难的。为了提供这样的解释，我们将进行原子分子动力学（MD）模拟的几个脂质双层系统嵌入自旋标记的脂质。MD轨迹将进行两种类型的定量分析，这将允许与报告的实验进行直接比较。首先，从模拟的自旋标签的动力学将被用来计算多频cw-EPR谱。其次，从电子自旋指向质子自旋的矢量的动力学将用于计算自旋之间的偶极相互作用的谱密度函数，由此将获得OE-DNP耦合因子。计算结果与实验结果的一致性将揭示高场OE-DNP增强所依赖的分子因素。另一方面，实验和计算之间可能存在的分歧将揭示MD模拟中的潜在缺陷。此外，我们希望将脂质双层的1H Over-hauser DNP实验扩展到DOPC脂质。这将允许探索自旋标记的脂质与先前研究的DMPC脂质之间的长度失配是否可能通过引起结构紊乱或改变内部水分子的可接近性和动力学而对实验观察到的DNP效率的低位置依赖性负责。