Optimizing a kinase assay for IKKbeta on an HTS station.

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• High-throughput screening (HTS) is crucial for identifying novel drug candidates.
• Kinase assays, particularly for targets like IKKbeta, require robust and optimized methodologies for efficient screening.
• Time-resolved fluorescence resonance energy transfer (TR-FRET) offers a sensitive detection method for biochemical assays.

Purpose of the Study:

• To automate and optimize a commercially available TR-FRET assay for IKKbeta on a high-throughput screening (HTS) platform.
• To evaluate assay performance parameters, including Z' factor, signal-to-noise ratio, and the impact of various reagents and conditions.
• To establish optimized conditions for efficient screening of potential IKKbeta inhibitors.

Main Methods:

• Adaptation of a commercial TR-FRET assay for IKKbeta onto an HTS station.
• Optimization of assay parameters: volumes, incubation times, and time-resolved fluorescence settings.
• Comparison of different kinase fusion tags (GST vs. poly-histidine), enzyme/substrate ratios, and DMSO concentrations.

Main Results:

• Glutathione S-transferase (GST)-fused IKKbeta exhibited significantly better signal-to-noise (S/N) ratios compared to the poly-histidine-tagged variant.
• Optimal enzyme and substrate concentrations were determined to be 2 nM and 50 nM, respectively.
• The assay demonstrated a high Z' factor of 0.881 under optimized conditions, allowing for the testing of 94 compounds in quadruplicate within 140 minutes.
• DMSO concentrations up to 1% had minimal impact on S/N, while 2% caused a ~15% decrease.

Conclusions:

• The optimized TR-FRET assay for IKKbeta is robust, sensitive, and suitable for high-throughput screening campaigns.
• The use of GST-fused IKKbeta is recommended for improved assay performance.
• The established assay conditions facilitate efficient and reliable screening of large compound libraries for IKKbeta modulators.