| Assay Method Information | |
| | Expression and Purification of Active Kinases |
| Description: | Full length CDPK1 was PCR amplified from a T. gondii RH cDNA library generated using the SMART cDNA synthesis kit (Clontech). The primers contained restriction sites that were used to directionally clone the PCR product, NdeI to XhoI, into the pET-22b(+) vector, in frame with a C-terminal hexahistidine tag. Single mutation of the codon corresponding to glycine 128 was achieved using the QuikChange II Site-Directed Mutagenesis Kit (Agilent Technologies), with specific primers designed according to manufacturer instructions. Plasmids were transformed into BL21(DE3)V2RpAcYc-LIC+LamP E. coli, which express the LamP phosphatase, as described previously. Following overnight growth in Terrific Broth at 37° C., cells were diluted 1:50 in fresh medium and cultured for 3 h at 37° C., then cooled to 15° C., induced by addition of 1 mM IPTG, and cultured overnight. Cells were lysed in CelLyticB solution (Sigma Aldrich), and proteins purified using HIS-select Nickel Affinity Gel following manufacturers instructions (Sigma-Aldrich). Purified proteins were dialyzed (50 mM Tris-HCl, pH 7.5, 150 mM NaCl, 0.125% Chelex 100) and stored in 20% glycerol at −80° C. Protein purity and concentration were determined by SDS-PAGE followed by staining with SYPRO Ruby (Invitrogen).Kinase assays were conducted using a peptide-based ELISA based on the syntide-2 peptide (Calbiochem). Syntide-2 peptide (10 mg/ml) was used to coat 96-well plates by overnight incubation in carbonate coating buffer (pH 9.6) at 4° C. Following washing in Tris tween (50 mM Tris-HCl, pH 7.5, 0.2% Tween20), plates were blocked with 3% BSA in Tris-tween for 2 h at room temperature, and further washing steps were conducted with Tris-tween. Kinase reactions were conducted at 30° C. for 20 min in kinase buffer (20 mM HEPES, pH 7.5, 10 mM MgCl2, 1 mM DTT, 2.5 mM CaCl2, 0.1 mM EGTA, 0.005% Tween20) containing appropriate amounts of ATP (Km for each enzyme) and enzyme dilutions (see below). Phosphorylated syntide peptides were detected with mAb MS-6E6 (MBL Intl. Corp.), followed by peroxidase-conjugated goat-anti-mouse IgG, developed with the substrate 3,3′,5,5′-Tetramethylbenzidine (TMB) and detected by absorbance at 450 nm. The activity of human calmodulin dependent kinase II alpha (aCaMKII) was tested using the CaM Kinase II Assay CycLex kit (MBL Intl. Corp.). |
| Affinity data for this assay | |
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