Aurora 2.0: A fluorogenic dye library for expanding the capability of protein-adaptive differential scanning fluorimetry (paDSF)

Differential Scanning Fluorimetry (DSF) is a biophysical assay that is used to estimate protein stability in vitro. In a DSF experiment, the increased fluorescence of a solvatochromatic dye, such as Sypro Orange, is used to detect the unfolding of a protein during heating. However, Sypro Orange is only compatible with a minority of proteins (< 30 %), limiting the scope of this method. We recently reported that protein-adaptive DSF (paDSF) can partially solve this problem, wherein the protein is initially pre-screened against ∼300 chemically diverse dyes, termed the Aurora collection. While this approach significantly improves the number of targets amenable to DSF, it still fails to produce protein-dye pairs for some proteins. Here, we report the expansion of the dye collection to Aurora 2.0, which includes a total of 517 structurally diverse molecules and multiple new chemotypes. To assess performance, these dyes were screened against a panel of ∼100 proteins, which were selected, in part, to represent the most challenging targets (e.g. small size). From this effort, Aurora 2.0 achieved an impressive success rate of 94 %, including producing dyes for some targets that were not matched in the original collection. These findings support the idea that larger, more chemically diverse libraries improve the likelihood of detecting melting transitions across a wider range of proteins. We propose that Aurora 2.0 makes paDSF an increasingly powerful method for studying protein stability, ligand binding and other biophysical properties in high throughput.