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NMR spectroscopy allows for the determination of high resolution structures, as well as being an efficient method for studying the dynamics of protein-protein and protein-peptide complexes. 15 N relaxation and H/D exchange experiments allow for the analysis of these structural dynamics at a residue specific level. Calmodulin (CaM) is a small cytosolic Ca 2+ binding protein that serves as a control element for many enzymes. An important target of CaM are the nitric oxide synthase (NOS) enzymes that play a major role in a number of key physiological and pathological processes. Studies have shown CaM facilitates a conformational shift in NOS allowing for efficient electron transfer through a process thought to be highly dynamic and at least in part controlled by several possible phosphorylation sites. This review highlights recent work performed on the CaM-NOS complexes using NMR spectroscopy and shows remarkable differences in the dynamic properties of CaM-NOS complexes at physiologically relevant Ca 2+ concentrations. It also shows key structural changes that affect the activity of NOS when interacting with apoCaM mutants and NOS posttranslational modifications are present.

The application of techniques based on magnetic resonance, specifically electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR), has provided a wealth of new information on RNA structures, as well as insights into the dynamics and function of these important biomolecules. NMR spectroscopy is very successful for determining the solution structures of small RNA domains, aptamers and ribozymes, and exploring their intramolecular dynamics and interactions with ligands. EPR-based methods have been used to map local dynamic and structural features of RNA, to explore different modes of RNA-ligand interaction, to obtain long-range structural restraints and to probe metal-ion-binding sites.