Biochemical Reactions in Microdroplets from a Theta Tip Capillary

Many enzymatic reactions catalyze reactants to products while populating short-lived intermediates. The development of time-resolved mass spectrometry offers high sensitivity and selectivity for studying the dynamic processes associated with the progress of the reaction in time. However, the rapid mixing of solutions during electrospray process is needed to probe the steady-state kinetics in faster processes. Here, we use droplet chemistry as a novel approach to create microdroplets from a theta glass capillary and follow the reaction after rapid mixing of enzyme, substrate, and cofactors that likely occurs in a few microseconds or less. In addition, we would like to compare the kinetics of enzyme-catalyzed reactions in microdroplets from that in bulk solution.2 The experimental investigation of enzymatic reactions in microdroplets will provide key insights to the reaction mechanism on the surface of water droplets.

Scheme 1. Cartoon representing theta tip capillary for nanoESI experiments.

1. Banerjee, S.; Zare, R. N.; Tibshirani, R. J.; Kunder, C. A.; Nolley, R.; Fan, R.; Brooks, J. D.; Sonn, G. A. Proceedings of the National Academy of Sciences 2017, 114, 3334.

2. Bain, R. M.; Sathyamoorthi, S.; Zare, R. N. Angewandte Chemie International Edition 2017, 56, 15083