Probing the Atomic Structure of Transient Protein Contacts by Paramagnetic Relaxation Enhancement Solution NMR.

Important biological processes, including enzyme catalysis, signaling, and protein folding, proceed through lowly populated (<5%) states that elude structural characterization by conventional techniques. Here, we describe the steps required for visualization of these sparsely populated conformations and transient protein-protein interactions using paramagnetic relaxation enhancement solution NMR. We describe experimental design, sample preparation, data acquisition and processing, and the basics of data analysis of structural ensembles.