Xenon-Protein Interactions: Characterization by X-Ray Crystallography and Hyper-CEST NMR.

The physiological activity of xenon has long been recognized, though the exact nature of its interactions with biomolecules remains poorly understood. Xe is an inert noble gas, but can act as a general anesthetic, most likely by binding internal hydrophobic cavities within proteins. Understanding Xe-protein interactions, therefore, can provide crucial insight regarding the mechanism of Xe anesthesia and potentially other general anesthetic agents. Historically, Xe-protein interactions have been studied primarily through X-ray crystallography and nuclear magnetic resonance (NMR). In this chapter, we first describe our methods for preparing Xe derivatives of protein crystals and identifying Xe-binding sites. Second, we detail our procedure for Xe hyper-CEST NMR spectroscopy, a versatile NMR technique well suited for characterizing the weak, transient nature of Xe-protein interactions.