Soraprazan (BYK61359)

Kinase experiment:

[3H]Soraprazan binding studies are carried out at 20°C. In saturation experiments to determine the Kd value, ion-leaky gastric vesicles (0.01-0.02 mg/mL) are resuspended in a buffer composed of 20 mM Tris-HCl, pH 7.0, 2 mM MgCl2, and 2 mM ATP (pH 7.0 by Tris) in the presence of increasing concentrations of [3H]soraprazan (0.1 nM-1 μM). Nonspecific binding is determined in the presence of a 100 fold excess of unlabeled soraprazan over the concentration range of [3H]soraprazan used. The enzyme suspension (1 mL) is incubated at 20°C for 30 min and rapidly filtered through a nitrocellulose membrane filter (0.45 μM) prewet with a solution composed of 20 mM Tris-HCl, pH 7.0, 10% polyethylene glycol 3350 that is placed on top of a glass fiber filter. The membrane is ished five times with 2.5 mL of a buffer composed of 20 mM Tris-HCl, pH 7.0, and 10% polyethylene glycol 3350 to remove unbound inhibitor. The membrane is put into a 20-mL scintillation vial, dimethylacetamide (0.5 mL) is added to dissolve the membrane, and 14 mL of scintillation solvent is added and counted. Binding of [3H]soraprazan is determined by subtracting the nonspecific binding of [3H]soraprazan, obtained in the presence of the 100-fold excess of nonradioactive soraprazan, from the amounts of [3H]soraprazan bound to the membrane in the absence of the cold inhibitor.

References:

[1]. Simon WA, et al. Soraprazan: setting new standards in inhibition of gastric acid secretion. J Pharmacol Exp Ther. 2007 Jun;321(3):866-74. Epub 2007 Mar 16.