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. Author manuscript; available in PMC: 2021 May 26.
Published in final edited form as: Isr J Chem. 2019 Sep 19;59(11-12):962–979. doi: 10.1002/ijch.201900080

Figure 4.

Figure 4.

Use of PRE and chemical shift perturbation to investigate the orientation and binding site of Ubq on paramagnetically doped fluoride-based SrF2 NPs. (A) The site-specific chemical shift perturbation (CSP) observed for Ubq upon transient adsorption to diamagnetic NPs. The diagram indicates that, for weakly associating proteins in the soft corona, only residues near the interaction site are perturbed. (B) Residue-specific CSPs observed for Ubq upon interaction with NPs. (CSP>0.02 ppm are highlighted in blue). (C) Large CSPs mapped on to the native structure of Ubq, revealing the interaction surface in blue. (D) In the presence of a paramagnetically doped NP, proximity to the stable radical electron induces relaxation in 1H spins. The diagram indicates that, in addition to experiencing CSP, such spins experience additional line broadening. (E) Intensity ratio (Ipara/Idia) of peaks in the presence and absence of a paramagnetic spin label. Lower intensities occur because of proximity to the NP surface, corresponding to the interaction site identified by PRE. (F) Graphical representation of Ubq Binding to SrF2 NPs. Reprinted with permission from Zanzoni et al.,[127] copyright 2016 American Chemical Society.