Assay Method Information

Assay Name:  The screening for GSK3beta kinase activity
Description:  Each compound is dissolved in DMSO as a 10 mM stock and used to prepare compound source plates. Serial dilution (1:3, 11-point dose-response curves from 10 μM to 0.0003 μM) and compound transfer was performed using the ECHO 550 (Labcyte, Sunnyvale, Calif.) into 1536-well black-walled round bottom plates (Corning). The GSK3β kinase assay is run using the Ser/Thr 09 peptide Z-lyte assay kit according to manufacturer's instructions (Life Technologies a Division of Thermo-Fisher). This is a non-radioactive assay using fluorescence resonance energy transfer (FRET) between coumarin and fluorescein to detect kinase activity which is represented as ratio of coumarin emission/fluorescein emission. Briefly, recombinant GSK3β kinase, ATP and Ser/Thr peptide 09 are prepared in 1ื Kinase buffer to final concentrations of 0.04 μg/mL, 46 μM, and 4 μM respectively. The mixture is allowed to incubate with the representative compounds for one hour at room temperature. All reactions were performed in duplicate. Unphosphorylated ( 0% Control ) and phosphorylated ( 100% control ) forms of Ser/Thr 18 serve as control reactions. After incubation, diluted Development Buffer is added to the reaction and allowed to further incubate for one hour at room temperature. The plate is read at Ex 400 Em 455 to detect the coumarin signal and Ex 400 Em 520 to measure the signal (EnVision Multilabel Plate Reader, PerkinElmer). The Emission ratio (Em) is calculated as a ratio of the coumarin (C) emission signal (at 445 nm)/Fluorescein (F) emission signal (at 520 nm). The percent phosphorylation is then calculated using the following formula: [1−((Em ratioืF100%)−C100%)/((C0%−C100%)+(Em ratioื(F100%−F0%)))]. Dose-response curves are generated and inhibitory concentration (IC50) values are calculated using non-linear regression curve fit in the Dotmatics' Studies Software (Bishops Stortford, UK).
Affinity data for this assay
 

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