Sielaff Lucca, Kehl Annemarie, Aden Anakin, Meyer Andreas, Bennati Marina
Research Group EPR Spectroscopy, Max Planck Institute for Multidisciplinary Sciences, Am Faßberg 11, 37077 Göttingen, Germany.
Institute of Physical Chemistry, Georg August University of Göttingen, Tammannstraße 6, 37077 Göttingen, Germany.
Sci Adv. 2025 Jul 25;11(30):eady5665. doi: 10.1126/sciadv.ady5665.
Hyperfine spectroscopy is a fundamental method in biophysical and material sciences to detect nuclear spins in vicinity of paramagnetic centers, leading to molecular structural information. Among variants of this experiment, only electron-nuclear double resonance (ENDOR) has been established to detect nuclei at interspin distances up to about 1.7 nanometers using F labels. This limit is dictated by the ENDOR linewidth of 10 to 30 kilohertz, which appeared insurmountable given dipolar broadening of the detected nucleus with the nuclear spin bath. Herein, we present ENDOR experiments based on nuclear sublevel coherence spectroscopy that push the boundaries of ENDOR sensitivity and resolution by one order of magnitude. In particular, we introduce an experiment, in which the electron-nuclear dipolar interaction can be exquisitely extracted from other nuclear broadening mechanisms, thus enabling to access distance distributions. This methodology paves the way for structural studies using F ENDOR in biomolecular systems. Moreover, it offers opportunities to access spin dynamics in electron-nuclear coupled spin systems.
超精细光谱学是生物物理和材料科学中用于检测顺磁中心附近核自旋的一种基本方法，可由此获得分子结构信息。在该实验的各种变体中，只有电子 - 核双共振（ENDOR）已被确立能够使用F标记检测自旋间距离达约1.7纳米的原子核。这一限制是由10至30千赫兹的ENDOR线宽决定的，鉴于检测到的原子核与核自旋浴的偶极展宽，这一限制似乎难以逾越。在此，我们展示了基于核子能级相干光谱学的ENDOR实验，其将ENDOR灵敏度和分辨率的边界提高了一个数量级。特别是，我们介绍了一种实验，其中电子 - 核偶极相互作用能够从其他核展宽机制中精确提取出来，从而能够获取距离分布。这种方法为在生物分子系统中使用F ENDOR进行结构研究铺平了道路。此外，它还为研究电子 - 核耦合自旋系统中的自旋动力学提供了机会。
