“…With restraints from multiple tagging sites, PCSs of backbone amide protons have been shown to be sufficient for 3D structure determinations of proteins (Schmitz et al, 2012;Yagi et al, 2013;Pilla et al, 2016Pilla et al, , 2017Cucuzza et al, 2021). Particularly appealing applications of PCSs have been the structure refinement of polypeptide segments in proteins of known 3D fold (Banci et al, 1996;Crick et al, 2015;Lescanne et al, 2018;Müntener et al, 2020) and the structural characterisation of the interfaces of protein-protein (Pintacuda et al, 2006;Keizers et al, 2010;Kobashigawa et al, 2012;Hass and Ubbink, 2014;de la Cruz et al, 2011;Brewer et al, 2015;Ubbink and Di Savino, 2018) and protein-ligand complexes (Pintacuda et al, 2007;Guan et al, 2013;Chen et al, 2016;Lescanne et al, 2018;Zimmermann et al, 2019), as the long-range nature of PCSs allows the attachment of the H. W. Orton et al: Localising nuclear spins by pseudocontact shifts from a single tagging site metal tags at a distance that is sufficiently far from the site of interest to avoid structural perturbations by the tag.…”