TBBz

TBBz has been used as a CK2 inhibitor in HeLa cells and rat septal neurons.

Cell-permeable CK2 inhibitor.

TBBz is a cell-permeable Casein Kinase-2 (CK2) inhibitor. CK2 inhibitors, 4,5,6,7-tetrabromobenzotriazole (TBBt, Sigma Cat. # T0826) and rabromobenzimidazole (TBBz), the latter of which was shown to discriminate between different molecular forms of CK2 in yeast. TBBt, with a pK(a) ~5, exists in solution at physiological pH almost exclusively (>99%) as the monoanion; whereas TBBz, with a pKa ~9, is predominantly (>95%) in the neutral form, both of obvious relevance to their modes of binding. In vitro, TBBt inhibits different forms of CK2 with Ki values ranging from 80 to 210 nM. TBBz discriminates better between CK2 forms, with Ki values ranging from 70-510 nM. TBBz is more effective than TBBt in inducing apoptosis and to a lesser degree, necrosis in transformed human cell lines. Dvelopment of shRNA strategies for the selective knockdown of the CK2α and CK2α′ isoforms reinforces the foregoing results, indicating that inhibition of CK2 leads to attenuation of proliferation.

TBBz is soluble in DMSO (60 deg C) at a concentration that is greater than 10 mg/ml.