Thermal Shift Assay for Small GTPase Stability Screening: Evaluation and Suitability.

Area of Science:

• Biochemistry
• Biophysics
• Pharmacology

Background:

• Thermal stability assays (TSA) are crucial for evaluating biotherapeutics.
• Differential scanning calorimetry (DSC) is a standard, but differential scanning fluorimetry (DSF) offers higher throughput for screening.
• Current DSF methods often lack sensitivity and present interpretation challenges.

Purpose of the Study:

• To compare the sensitivity and utility of three thermal stability probes: SYPRO Orange, 8-anilino-1-naphthalenesulfonic acid (ANS), and the Protein-Probe.
• To assess these probes for studying small GTPase stability, using KRAS as a model.
• To evaluate the probes' effectiveness in characterizing drug candidates, including small molecules and Designed Ankyrin Repeat Proteins.

Main Methods:

• Differential scanning fluorimetry (DSF) was employed to measure protein thermal stability.
• Three fluorescent probes (SYPRO Orange, ANS, Protein-Probe) were compared.
• Studies focused on KRAS protein stability in the presence of various drug candidates.

Main Results:

• The Protein-Probe demonstrated higher sensitivity and could be used at lower concentrations compared to SYPRO Orange and ANS.
• The Protein-Probe enabled effective drug screening at the nanomolar level for both non-covalent and covalent drug candidates.
• TSA profiles provided valuable biochemical insights into KRAS stability and drug interactions.

Conclusions:

• The Protein-Probe represents a significant advancement in thermal stability assays for biotherapeutic drug discovery.
• Its enhanced sensitivity and lower concentration requirements make it ideal for high-throughput screening and detailed mechanistic studies.
• This probe facilitates the characterization of drug effects on protein stability, aiding in the development of new therapeutics.