Two Tags in One Probe: Combining Fluorescence- and Biotin-based Detection of the Trypanosomal Cysteine Protease Rhodesain.

Rhodesain is the major cysteine protease of the protozoan parasite Trypanosoma brucei and a therapeutic target for sleeping sickness, a fatal neglected tropical disease. We designed, synthesized and characterized a bimodal activity-based probe that binds to and inactivates rhodesain. This probe exhibited an irreversible mode of action and extraordinary potency for the target protease with a kinac /Ki value of 37,000 M-1 s-1 . Two reporter tags, a fluorescent coumarin moiety and a biotin affinity label, were incorporated into the probe and enabled highly sensitive detection of rhodesain in a complex proteome by in-gel fluorescence and on-blot chemiluminescence. Furthermore, the probe was employed for microseparation and quantification of rhodesain and for inhibitor screening using a competition assay. The developed bimodal rhodesain probe represents a new proteomic tool for studying Trypanosoma pathobiochemistry and antitrypanosomal drug discovery.

Structure-Stability Relationship of NLRP3 Inflammasome-Inhibiting Sulfonylureas.

In recent drug development efforts, particular emphasis has been devoted to the chemical interference with the NLRP3 inflammasome. A series of 12 tailored sulfonylureas was designed, prepared through convergent syntheses with a final sodium hydride-promoted reaction of isocyanates and sulfonamides, and subjected to a systematic, high-performance liquid chromatography-based survey of the chemical stability, a critical issue of sulfonylureas in terms of preparation, storage, and application. NLRP3 binding was determined by surface plasmon resonance spectroscopy. Sulfonylurea 2 was identified to be equipotent and similarly stable compared to the prototypical NLRP3 inhibitor MCC950.

Influence of Linker Attachment Points on the Stability and Neosubstrate Degradation of Cereblon Ligands.

Proteolysis targeting chimeras (PROTACs) hijacking the cereblon (CRBN) E3 ubiquitin ligase have emerged as a novel paradigm in drug development. Herein we found that linker attachment points of CRBN ligands highly affect their aqueous stability and neosubstrate degradation features. This work provides a blueprint for the assembly of future heterodimeric CRBN-based degraders with tailored properties.