High-throughput label-free enzymatic bioassays using automated desi-ms

A system for analyzing one or more enzymatic reactions, the system comprising:

• a fluid handling system that includes a pinning device configured to interact with a microwell plate and prepare a plurality of discrete spots on a substrate, wherein each of the discrete spots comprises a substrate and a product of one or more enzymatic reactions, wherein both of the substrate and the product of the one or more enzymatic reactions are label-free;
• an ionization source configured to direct sequentially a discharge from the ionization source onto each of the plurality of discrete spots to sequentially desorb the substrate and/or product from each of the discrete spots and sequentially generate ions of the substrate and/or product from each of the discrete spots;
• and
• a mass spectrometer positioned to receive the generated ions of the substrate and/or product from each of the discrete spots and analyze sequentially the ions of the substrate and/or product from each of the discrete spots in the mass spectrometer to thereby analyzing the one or more enzymatic reactions.