Solvent PRE as a biomolecular investigation tool: focusing on structurally heterogeneous proteins and IDPs

NMR-based solvent paramagnetic relaxation enhancement (sPRE) has become a widely used tool for the study of biomolecules. Its appeal lies in the simplicity of its preparation: a soluble paramagnetic probe is added directly to the sample solution, inducing a concentration-dependent increase in relaxation rates that depends on the properties of the probe, the biomolecule, and the distance of the probe from the biomolecular surface. By measuring the relaxation rates of different nuclei at increasing concentrations of the paramagnetic agent, sPREs can be quantified along the protein sequence to map different conformations, probe solvent accessibility and weak interactions. Such information is crucial to study how medically relevant proteins carry out their biological function. In this context, we aim to assess the applicability of this approach to develop a solid methodology for the characterization of structurally heterogeneous proteins.