Smaller is better: nanobodies meet NMR.

Nanobodies, the single-domain antigen-binding fragments derived from camelid heavy chain antibodies, have emerged as powerful tools in structural biology. Their small size, high stability, and ability to bind with exceptional specificity make them ideal for applications in nuclear magnetic resonance (NMR) spectroscopy. In protein NMR, nanobodies can serve as chaperones to stabilize flexible regions, reduce conformational heterogeneity, and enhance spectral quality. They facilitate the study of challenging targets such as membrane proteins, large complexes, and intrinsically disordered proteins by improving solubility and enabling selective labeling strategies. Furthermore, nanobody-assisted NMR spectroscopy provides unique opportunities for probing dynamic interactions and conformational states under near-physiological conditions. This review summarizes recent advances in nanobody engineering for NMR studies, including the synthetic nanobodies, highlights the nanobodies' role in overcoming size and stability limitations, and discusses future directions for integrating nanobodies into emerging NMR methodologies, with an emphasis on protein dynamics and protein-protein interactions in the context of drug discovery.