Optimisation of plate-based Affinity Selection Mass Spectrometry (ASMS) method and application to novel oncology drug target

Abstract

Affinity selection Mass Spectrometry (AS-MS), is a label-free,
affinity-based high-throughput screening technology which can rapidly profile
large numbers of compounds for direct binding to targets of interest. It has
been viewed as an increasingly useful screening capability within AstraZeneca
as our portfolio grows to include an increasing number of enzymatically inert
targets. Our in-house, solution-based AS-MS method utilises plate-based size
exclusion chromatography (SEC) to separate unbound samples from protein-ligand
complexes with an Acoustic Mist Ionisation-MS (AMI-MS) endpoint enabling
identification of binding compounds. Initial application of this approach
identified several caveats that could limit the success of the technique. These
primarily included low recovery of target protein through the SEC column and
high false positive rates. Accordingly a comprehensive round of process
optimisation was performed. Through investigation of alternative conditions we
have identified our preferred SEC column resin and buffer components. These have
been validated in a series of test screens, prior to their implementation against
a novel, high value oncology drug target. Here we will describe our findings and
discuss future plans.