Screening compounds of interest against USP5 Zf-UBD with a surface plasmon resonance assay

It’s been a busy couple of weeks in and out of the lab for me which is why it’s been some time since my last post. I previously identified small molecule compounds of interest using a 19F NMR spectroscopy assay. To quantify and validate these small molecule compounds, I used a surface plasmon resonance (SPR) Read More …

Compounds of interest identified by screening a focused library against USP5 Zf-UBD with a 19F NMR assay

In my last post, I developed a low-throughput 19F NMR screening assay against USP5 Zf-UBD, where ligand binding of a ubiquitin peptide was detected by perturbations in the resonance of a fluorinated tryptophan at the binding pocket. I recently screened the first batch of compounds that Ivan Franzoni and Renato Freitas, post-docs at the University Read More …

USP5 Zf-UBD Differential Scanning Fluorimetry Assay Development #3

In my last post, I determined that fluorescence polarization with different lengths of ubiquitin peptides was not a viable assay to screen compounds. I wanted to see if the ubiquitin peptides of different lengths resulted in a thermal shift of the USP5 Zf-UBD in a differential scanning fluorimetry assay. Experimental details are on Zenodo. As Read More …

USP5 Zf-UBD Fluorescence Polarization Displacement Assay #3

In previous experiments, a FITC-RLRGG ubiquitin peptide had a Kd of ~55 µM for USP5 Zf-UBD. Different lengths of ubiquitin peptides were designed to see if increasing the peptide length resulted in a gain in affinity for the protein domain in the FP assay: LRLRGG, RAHGLRLRGG, RAHGRAKHGLRLRGG. The 6-mer peptide, LRLRGG, is the native C-terminal Read More …

Crystallization of USP5 Zf-UBD #2

In my last post, I analyzed a structure of USP5 zinc-finger ubiquitin binding domain with a cysteine-glutathione disulphide bond. These crystals were not suitable for ligand soaking due to the formation of a disulphide bond at Cys195 with a glutathione additive that occupies the ubiquitin binding pocket in the adjacent molecule in the crystal lattice. Read More …