Millisecond Mix-and-Quench Crystallography (MMQX) Enables Time-Resolved Studies of PEPCK With Remote Data Collection

Time-resolved crystallography of biomolecules in action has advanced rapidly as methods for serial crystallography have improved, but the large number of crystals and complex experimental infrastructure required remain serious obstacles to widespread application. We have developed Millisecond Mix-and-Quench crystallography (MMQX), which yields millisecond time-resolved data using far fewer crystals and routine remote synchrotron data collection. To demonstrate the capabilities of MMQX, the conversion of oxaloacetic acid to phosphoenolpyruvate by phosphoenolpyruvate carboxykinase is observed with a time resolution of 40 ms. MMQX, by lowering the entry barrier to time-resolved crystallography, should enable broad expansion in structural studies of protein dynamics.