biostudies-literatureYang HNIH Office of the DirectorDivision of Molecular and Cellular BiosciencesUniversity of Wisconsin-MadisonNational Institute of General Medical SciencesNIGMS NIH HHSNIH HHS11608-11619https://www.ebi.ac.uk/biostudies/studies/S-EPMC9577358biostudies-literatureUnknown144(26)NMR spectroscopy is a powerful tool to investigate molecular structure and dynamics. The poor sensitivity of this technique, however, limits its ability to tackle questions requiring dilute samples. Low-concentration photochemically induced dynamic nuclear polarization (LC-photo-CIDNP) is an optically enhanced NMR technology capable of addressing the above challenge by increasing the detection limit of aromatic amino acids in solution up to 1000-fold, either in isolation or within proteins. Here, we show that the absence of NMR-active nuclei close to a magnetically active site of interest (e.g., the structurally diagnostic ¹H^α-¹³C^α pair of amino acids) is expected to significantly increase LC-photo-CIDNP hyperpolarization. Then, we exploit the spJournal of the American Chemical SocietySelective Isotope Labeling and LC-Photo-CIDNP Enable NMR Spectroscopy at Low-Nanomolar Concentration.PMC9577358R01GM125995MCB 2124672S10OD012245R01 GM125995S10 OD012245Bridge FundsYang HDang HHCavagnero SLi SGuzman-Luna VThompson CMMickles CASugisaki KfalseSelective Isotope Labeling and LC-Photo-CIDNP Enable NMR Spectroscopy at Low-Nanomolar Concentration.NMR spectroscopy is a powerful tool to investigate molecular structure and dynamics. The poor sensitivity of this technique, however, limits its ability to tackle questions requiring dilute samples. Low-concentration photochemically induced dynamic nuclear polarization (LC-photo-CIDNP) is an optically enhanced NMR technology capable of addressing the above challenge by increasing the detection limit of aromatic amino acids in solution up to 1000-fold, either in isolation or within proteins. Here, we show that the absence of NMR-active nuclei close to a magnetically active site of interest (e.g., the structurally diagnostic ¹H^α-¹³C^α pair of amino acids) is expected to significantly increase LC-photo-CIDNP hyperpolarization. Then, we exploit the sp2022-01-01T00:00:00Z2022 Jul2025-04-05T12:21:01.339Z2025-04-05T12:21:01.339ZS-EPMC95773583570031710.1021/jacs.2c01809