Conformational freedom of metalloproteins revealed by paramagnetism-assisted NMR

In many biologically relevant cases protein–ligand or protein–protein recognition occurs thanks to the availability of multiple conformational states of at least one of the partners. Paramagnetism-assisted NMR is a powerful tool to address the conformational freedom of proteins. Appropriate experiments and theoretical interpretation permit the characterization of biologically relevant protein–protein interactions in solution. The paradigmatic examples of two-domain metalloproteins such as calmodulin (CaM) or two-domain metalloenzymes such as matrix metalloproteinases (MMP) are discussed.