Assay Method Information

Assay Name:  CDK2/CycE Kinase Assay
Description:  N-terminally His6-tagged recombinant catalytic domain of human Bub1 (amino acids 704-1085), expressed in insect cells (Hi5) and purified by Ni-NTA affinity chromatography and subsequent size exclusion chromatography, was used as enzyme. As substrate for the kinase reaction the biotinylated peptide biotin-Ahx-VLLPKKSFAEPG (C-terminus in amid form) was used which can be purchased e.g. form the company Biosyntan (Berlin, Germany). For the assay 50 nl of a 100 fold concentrated solution of the test compound in DMSO was pipetted into a black low volume 384 well microtiter plate (Greiner Bio-One, Frickenhausen, Germany), 2 ul of a solution of Bub1 in aqueous assay buffer [50 mM Tris/HCl pH 7.5, 10 mM magnesium chloride (MgCl2), 200 mM potassium chloride (KCl), 1.0 mM dithiothreitol (DTT), 0.1 mM sodium ortho-vanadate, 1% (v/v) glycerol, 0.01% (w/v) bovine serum albumine (BSA), 0.005% (v/v) Trition X-100 (Sigma), 1x Complete EDTA-free protease inhibitor mixture (Roche)] were added and the mixture was incubated for 15 min at 22° C. to allow pre-binding of the test compounds to the enzyme before the start of the kinase reaction. Then the kinase reaction was started by the addition of 3 ul of a solution of adenosine-tri-phosphate (ATP, 16.7 uM=>final conc. in the 5 ul assay volume is 10 uM) and substrate (1.67 uM=>final conc. in the 5 ul assay volume is 1 uM) in assay buffer and the resulting mixture was incubated for a reaction time of 60 min at 22° C. The concentration of Bub1 was adjusted depending of the activity of the enzyme lot and was chosen appropriate to have the assay in the linear range, typical concentrations were in the range of 200 ng/ml. The reaction was stopped by the addition of 5 ul of a solution of TR-FRET detection reagents (0.2 uM streptavidine-XL665 [Cisbio Bioassays, Codolet, France] and 1 nM anti-phosho-Serine antibody [Merck Millipore, cat. #35-001] and 0.4 nM LANCE EU-W1024 labeled anti-mouse IgG antibody [Perkin-Elmer, product no. AD0077, as an alternative a Terbium-cryptate-labeled anti-mouse IgG antibody from Cisbio Bioassays can be used]) in an aqueous EDTA-solution (50 mM EDTA, 0.2% (w/v) bovine serum albumin in 100 mM HEPES pH 7.5). The resulting mixture was incubated 1 h at 22° C. to allow the formation of complex between the phosphorylated biotinylated peptide and the detection reagents.
Affinity data for this assay
 

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