| Assay Method Information | |
| | Metalloenzyme Activity |
| Description: | V79-4 cells expressing recombinant andrenodoxin and andrenodoxin reductase with either recombinant human CYP11B2 or CYP11B1 were prepared according to methods previously described (LaSala et al 2009 Anal Bioch 394:56-61). An enzyme enriched microsomal fraction was prepared from cellular lysates and subsequently used as the enzyme source for determining inhibitor IC50s. The substrate Km values were experimentally determined for 11-deoxycorticosterone (CYP11B2 substrate) and 11-deoxycortisol (CYP11B1 substrate). Enzyme assays for inhibitor screening employed CYP11B2 and CYP11B1 enzyme enriched microsomes and were run at the Km of the respective substrates. Products of the enzyme reactions, aldosterone for CYP11B2 or cortisol for CYP11B1, were measured by LC-MS. Assays were run under conditions of less than 20% substrate turnover. Inhibitor IC50s were generated by determining the product formation in the absence or presence of inhibitor at various concentrations. In the absence of the test compound, the product formed (Pt) in each data set was defined as 100% activity. In the absence of enzyme, the product formed (Pb) in each data set was defined as 0% activity. The percent activity in the presence of each inhibitor was calculated according to the following equation: % activity=(P−Pb)/(Pt−Pb), where P=the product formed in the presence of the inhibitor. The IC50 value was defined as the inhibitor concentration causing a 50% decrease in activity relative to the no inhibitor control reaction. |
| Affinity data for this assay | |
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