An electrospray ms-coupled microfluidic device for sub-second hydrogen/deuterium exchange pulse-labelling reveals allosteric effects in enzyme inhibition

In this work, we introduce an integrated, electrospray mass spectrometry-coupled microfluidic chip that supports the complete workflow for 'bottom up' hydrogen/deuterium exchange (HDX) pulse labelling experiments. HDX pulse labelling is used to measure structural changes in proteins that occur after the initiation of a reaction, most commonly folding. In the present case, we demonstrate the device on the β-lactamase enzyme TEM-1, identifying active site changes that occur upon acylation by a covalent inhibitor and subtle changes in conformational dynamics that occur away from the active site over a period of several second after the inhibitor is bound. Our results demonstrate the power of microfluidics-enabled sub-second HDX pulse labelling as a tool for studying allostery and show some intriguing correlations with mutagenesis studies.