Funding Acknowledgment: The SGC is a registered charity (number 1097737) that receives funds from AbbVie, Bayer Pharma AG, Boehringer Ingelheim, Canada Foundation for Innovation, Eshelman Institute for Innovation, Genome Canada through Ontario Genomics Institute [OGI-055], Innovative Medicines Initiative (EU/EFPIA) [ULTRA-DD grant no. 115766], Janssen, Merck KGaA, Darmstadt, Germany, MSD, Novartis Pharma AG, Ontario Ministry of Research, Innovation and Science (MRIS), Pfizer, São Paulo Research Foundation-FAPESP, Takeda, and Wellcome.

The expression and purification of USP5171-290 in media supplemented with 5-fluoro-tryptophan. Mass spectrometry, differential scanning fluorimetry and fluorescence polarization assays were used to verify label incorporation, protein folding and ubiquitin peptide binding respectively. Preliminary 19F NMR experiments were completed with the purified protein to determine if there are perturbations in one of the 19F resonances with a ubiquitin peptide, LRLRGG.