Assay Method Information

Assay Name:  Inhibitory Activity Assay
Description:  The inhibition of CYP17A1 by the test compounds was evaluated using a recombinant enzyme. Human CYP17A1 was expressed in E. coli (Ehmer, P. B. et al.; J. Steroid Biochem. Mol. Biol., 75, 57-63 (2000)). The microsomal fraction and 140 μL of phosphate buffer (50 mM Na phosphate, 1 mM MgCl2, 0.1 mM EDTA, 0.1 mM dithiothreitol, pH 7.4) were preincubated separately with a mixture of progesterone (24.95 μM) and 3H-progesterone (0.05 μM, 101.3 Ci/mmol), 50 μM of an NADPH regeneration system (in phosphate buffer with 10 mM NADP+, 100 mM glucose 6-phosphate and 2.5 U of glucose 6-phosphate dehydrogenase) and the appropriate test substances (in 5 μl of DMSO) at 37° C. for 5 minutes. The reaction was started by addition of the enzyme and, after 30 minutes of incubation at 37° C., stopped by addition of 50 μl of 1N hydrochloric acid.The steroids were extracted with ethyl acetate. After evaporation of the organic phase, the steroids were taken up in acetonitrile.
Affinity data for this assay
 

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