Assay Method Information

Assay Name:  Caliper Assay
Description:  A kinase selectivity panel which measures substrate peptide phosphorylation was set-up for wild-type ALK2 (aa172-499), ALK2 FOP mutant (aa172-499 R206H), ALK1 (aa166-493), ALK5 (aa162-503) and ALK6 (aa168-495). The technology used for the described assay is based on the separation and quantification of substrate and product in an electrical field. In the course of the kinase reaction the peptide substrate is phosphorylated by a kinase. The transfer of a phosphate residue also causes the introduction of two additional negative charges and hence to a change in the net charge of the phospho-peptide compared to the unphosphorylated peptide. Due to this difference in charge the phosphorylated und unphosphorylated peptides migrate with different velocities in an electrical field.In the applied method, this separation takes place inside a chip that contains a complex capillary system for simultaneous analysis of 12 samples ( 12-sipper chip , Caliper Technologies Corp., Mountain View, USA). In order to allow the detection and quantification of the peptides in the capillary system, the peptides carry a fluorescent label (fluorescein). With this label the peptides can be quantified by fluorescence intensity through the instruments laser and detection system (LC3000, Caliper Life Sciences).The assays were performed in 384-well, low volume microtiter assay plates in a final reaction volume of 9 ul. Dose-response curves were generated by incubating 10 nM of each kinase together with 2 μm of the fluorescently labeled substrate peptide 5-Fluo-Ahx-KKYQAEEN-T-YDEYENKK-amid (10 mM stock solution in DMSO) in 50 mM Hepes pH 7.5, 0.02% Tween 20, 0.02% BSA, 1 mM DTT, 10 m Na3VO4, 10 mM If-Glycerolphosphate, 1 mM MgCl2, 12 mM MnCl2 (ALK1 and ALK6 7 mM) and 15 μm ATP for 60 min at 30° C. in the presence or absence of compound diluted in DMSO. Kinase reaction were terminated by adding 15 ul STOP buffer (100 mM HEPES pH 7.5, 5% DMSO, 0.1% Caliper coating reagent, 10 mM EDTA, and 0.015% Brij35.Plates with terminated kinase reactions were transferred to the Caliper LC3000 workstation (Caliper Technologies Corp., Mountain View, USA) for reading. The relative amount of phosphorylated peptide r, was calculated using the heights of the substrate peak, s, and the product peak, p: r=p/(p+s).
Affinity data for this assay
 

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