Combining Label‐free and Flourometric Functional Assays with Biophysical Binding Assays in Drug Discovery: A Comparison of Positives from an HTS Campaign

Abstract

HTS campaigns push functional assays to their limits for multiple reasons. As such, labeled substrates and secondary detection methods that minimize interference issues are often employed. Fluorescent labeling of a substrate results in the generation of a substrate that no longer resembles the physiological target. Secondary or tertiary detection techniques often result in an assay where initial velocity requirements are lost. In an ideal world, one would the physiological substrates requiring the implementation of label‐free system. The reality of label free‐detection are the amplification of interference issues and/or use substrate concentrations well above the KM‐value. The coupling of high‐throughput mass spectroscopy (HTMS) in a functional assay eliminates these issues and as such one can use substrates that more closely reflect the in vivo condition. HTMS assays are sensitive and they eliminate complications from secondary detection methods. HTMS allows for the examination of the substrates and products from multi‐functional enzymes reactions independently. In the present study, functional assays are coupled with a label‐free biophysical binding assay (ThermofluorTM). The overlap between these orthogonal in vitro technologies enables rapid lead generation and lead optimization of compounds that can progress into full development.