Abstract

Mass spectrometry has proven to be a powerful tool to enable label-free analysis of biochemical activities. The current challenge is improving sample preparation procedures which limit throughput and introduce restrictions that impact data quality. The combination of self-assembled monolayers of alkanethiolates on gold in a high-density biochip array format with MALDI mass spec – a technique termed SAMDI – offers several solutions for high-throughput analysis of biochemical and cellular activities. Here we present the application of SAMDI in an affinity selection format to screen and characterize candidate molecular glues. Next, we describe the development of a duplexed assay to simultaneously measure and distinguish tyrosine and threonine phosphatase activities from cells. We use the optimized duplexed assay to screen 50,000 small molecules to identify a series of threonine phosphatase specific inhibitors. Taken together, SAMDI is a flexible platform that offers solutions for characterizing virtually any enzyme activity, identifying ligands binding to diverse protein and oligonucleotide targets, and accelerating drug discovery from purified targets to cells.