Mahawaththa, MithunOrton, HenryAdekoya, IbidolapoHuber, ThomasOtting, GottfriedNitsche, Christoph2022-08-021359-7345http://hdl.handle.net/1885/270115Arsenical probes enable structural studies of proteins. We report the first organoarsenic probes for nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) spectroscopy to study proteins in solutions. These probes can be attached to irregular loop regions. A lanthanide-binding tag induces sizable pseudocontact shifts in protein NMR spectra of a magnitude never observed for small paramagnetic probes before.C. N. thanks the Alexander von Humboldt Foundation for a Feodor Lynen fellowship and the Australian Research Council (ARC) for a Discovery Early Career Research Award (DE190100015). G. O. gratefully acknowledges an ARC Laureate Fellowship (project FL170100019) and research support (project CE200100012). Financial support by the Australian Research Council for project funding (DP200100348) is gratefully acknowledged.application/pdfen-AUThis journal is © The Royal Society of Chemistry 2022nuclear magnetic resonancebiomolecular2022-01-1310.1039/d1cc06497e