VHL cooperativity assay – fluorescence polarization (FP) based service
Evaluate PROTAC cooperativity and ternary complex formation using our proprietary fluorescent probe CELT-504.
A fluorescence polarization-based service designed to evaluate how a protein of interest (POI) influences the apparent binding affinity of VHL-recruiting PROTACs, providing quantitative cooperativity data to support PROTAC characterization and optimization.
For full technical details, assay parameters and experimental validation, see the VHL cooperativity assay service brochure.
What is this service?
Celtarys’ VHL cooperativity assay service is a fluorescence polarization (FP)-based assay designed to evaluate how a protein of interest (POI) influences the apparent binding affinity of VHL-recruiting PROTACs for the VHL E3 ligase complex (VBC).
Using our high-affinity fluorescent tracer CELT-504, the assay compares PROTAC displacement curves in the absence (binary condition) and presence (ternary condition) of the POI. This enables the determination of IC₅₀, apparent Ki values and cooperativity factors (α), providing insights into target-dependent PROTAC behavior and ternary complex formation.
The assay has been validated using the well-characterized PROTAC MZ1 and BRD4-BD2 as the protein of interest, demonstrating strong positive cooperativity (α ≈ 23.6), consistent with published studies.
Binary binding assessment: PROTAC displacement curves are generated in the absence of the protein of interest (POI) to determine the apparent binding affinity for VHL, including IC₅₀ and Ki values.
Ternary binding & cooperativity assessment:The same PROTAC is evaluated in the presence of the selected POI. Binary and ternary binding affinities are compared to calculate the cooperativity factor (α) and identify positive, neutral or negative cooperativity.
Sample requirements
Customers are required to provide their PROTAC samples, preferably as 10 mM stock solutions in DMSO or as lyophilized solids.
The protein of interest (POI) can either be supplied by the customer or sourced by Celtarys upon request. Any additional protein procurement costs will be included in the quotation.
Please contact us to discuss your experimental requirements and sample preparation before shipment.
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