Optimizing a kinase assay for IKKbeta on an HTS station.
Using a commercially available time-resolved fluorescence resonance energy transfer (TR-FRET)-based assay for IKKbeta, the authors have automated the assay procedure on a high-throughput screening station to carry out screening campaigns on multiwell plates. They have determined the Z' factor and optimized volumes, times, and time-resolved fluorescence parameters. They have also compared 2 kinases with different fusion tags, the influence of different enzyme/substrate ratios and of DMSO presence at different concentration. The authors found that glutathione S-transferase (GST)-fused IKKbeta shows better signal-to-noise (S/N) ratios over the poly-histidine-tagged variant. The substrate can be used at 50 nM with optimal performances when the enzyme is used at 2 nM. DMSO at 0.2% and 1% only slightly affects the S/N ratio, whereas when used at 2%, the final concentration deriving from a 50-fold dilution from a 5-mM stock solution in pure solvent, S/N undergoes a decrease of about 15%. Under the optimized conditions, the assay Z' factor calculated over 192 data points has an optimized value of 0.881 and allows the testing of 94 molecules in quadruplicate in 140 min.
Istituto di Biostrutture e Bioimmagini, CNR, 80134 Napoli, Italy.
Nunzianna
N
Doti
Daniela
D
Marasco
Carlo
C
Pedone
Marco
M
Sabatella
Menotti
M
Ruvo
D057075:Enzyme Assays / Q000379:methods*; D031541:Fluorescence Resonance Energy Transfer; D005982:Glutathione Transferase / Q000378:metabolism; D057166:High-Throughput Screening Assays / Q000379:methods*; D051550:I-kappa B Kinase / Q000378:metabolism*; D020672:I-kappa B Proteins / Q000378:metabolism; D013997:Time Factors
C083487:I kappa B beta protein; D020672:I-kappa B Proteins; D005982:Glutathione Transferase; D051550:I-kappa B Kinase