Journal of magnetic resonance (San Diego, Calif. : 1997)最新文献

Nuclear magnetic resonance (NMR) spectroscopy is an important analytical tool for probing molecular structures and interactions. For high complexity samples, multidimensional spectroscopy is essential for improving the resolution of NMR data. However, multidimensional experiments cost significant experimental time which scales with the number of indirect points. This is particularly challenging when dealing with highly dispersed nuclei, such as ¹³C, due to the large chemical shift range, with large regions that are spectrally empty. Herein, we describe a method for limiting the spectral width of dipolar based multidimensional NMR experiments in the indirect dimension in a manner that can be easily integrated into relaxation and distance measuring schemes. We demonstrate the acquisition of narrow strips of broadband homonuclear recoupling ¹³C-¹³C correlation spectra on a range of biomolecular and cellular samples, allowing targeted acquisition of high-resolution spectra of the region of interest with a significant reduction in the acquisition time. We also demonstrate the use of the spectral-band-selective method for allowing fast acquisition of RFDR build-up experiments. The band-selective method is easy to implement in any dipolar-based multidimensional pulse sequence by an addition of one pulse per band-selected indirect dimension and a slight modification of the phase cycle.

NMR is widely employed to investigate the structure and dynamics of biomolecules such as proteins and nucleic acids, owing to its unique ability to resolve signals from individual residue sites and thereby provide site-specific information. Among NMR spin probes, fluorine-19 (¹⁹F) has been extensively applied across diverse systems because of its favorable properties, including spin 1/2, 100 % natural abundance, low background signals, and high sensitivity to small variations in chemical environments. While advances in labeling strategies have expanded the applications of ¹⁹F, relatively less attention has been paid to its intrinsic relaxation properties; namely, how the longitudinal and transverse relaxation rates of ¹⁹F are defined and what types of magnetic interactions govern these relaxation processes. A major difficulty lies in the fact that ¹⁹F relaxation is affected by both intra- and inter-residual ¹H-¹⁹F dipole-dipole interactions as well as by its intrinsically large chemical shift anisotropy, complicating the quantitative interpretation of relaxation behavior. In this perspective, we revisit the theoretical background of ¹⁹F relaxation measurements, with particular focus on ¹H-¹⁹F interactions, aiming to provide guidelines for interpreting ¹⁹F NMR relaxation data and for developing novel experimental strategies.

Electrostatic interactions are central to biomolecular structure, dynamics, and function, yet experimentally probing local electrostatic potentials with residue-level resolution remains challenging. Solvent paramagnetic relaxation enhancement (sPRE) offers a powerful nuclear magnetic resonance (NMR) approach to directly quantify near-surface electrostatic environments without requiring structural information. In this review, we outline the theoretical framework underlying sPRE, emphasizing recent advances in spectral density analysis, spatial decomposition, and the influence of intermolecular potentials. We discuss the effective near-surface electrostatic potential (ENS), a derived quantity that captures local electrostatic fields by comparing transverse relaxation rates induced by paramagnetic cosolutes of differing charge. Applications to proteins, nucleic acids, and intrinsically disordered systems highlight the ability of sPRE and ENS to reveal electrostatic modulation in complex biological contexts, including phase separation, ion atmosphere structure, and protein-nucleic acid interactions. We also examine current limitations and provide a theoretical basis for interpreting ENS, offering perspectives for future methodological developments in electrostatics mapping by NMR.