Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
H/D exchange reactions in the high vacuum of a mass spectrometer reveal how crown ethers move between ammonium ion binding sites of an oligolysine peptide. This study enables the dynamics of non-covalent interactions to be probed in a unique environment and could be applied to more complex artificial or natural systems.