NMR-Based Strategies to Elucidate Bioactive Conformations of Weakly Binding Ligands

Key processes in molecular biology are regulated by interactions between biomolecules. Protein-proteinand protein-ligand interactions, e.g., in signal transduction pathways, rely on the subtle interactionsbetween atoms at the binding interface of the involved molecules. Because biomolecules often havemany interacting partners, these interactions are not necessarily strong. The study of molecularrecognition gives insight into the complex network of signaling in life and is the basis of structure-baseddrug design.In the situation where the interaction is weak, one of the traditional methods that can be appliedto obtain structural information (internuclear distances) of the bound ligand is the so-called transferredNOE (trNOE) method. Recently, it became possible to use transferred cross-correlated relaxation (trCCR)to directly measure dihedral angles. The combined use of these two techniques significantly improvesthe precision of the structure determination of ligands weakly bound to macromolecules.The application of these techniques will be discussed in detail for a peptide derived fromIKKβ bound to the protein NEMO that plays an important rolein the NFκB pathway.