LAUSR

Much of our understanding of protein structure and mechanistic function has been derived from static high‐resolution structures. As structural biology has continued to evolve it has become clear that high‐resolution structures alone are unable to fully capture the mechanistic basis for protein structure and function in solution. Recently Hydrogen/Deuterium‐exchange Mass Spectrometry (HDX‐MS) has developed into a powerful and versatile tool for structural biologists that provides novel insights into protein structure and function. HDX‐MS enables direct monitoring of a protein's structural fluctuations and conformational changes under native conditions in solution even as it is carrying out its functions. In this review, we focus on the use of HDX‐MS to monitor these dynamic changes in proteins. We examine how HDX‐MS has been applied to study protein structure and function in systems ranging from large, complex assemblies to intrinsically disordered proteins, and we discuss its use in probing conformational changes during protein folding and catalytic function.