| Assay Method Information | |
| | Carbonic Anhydrase Assay |
| Description: | The principle of the assay is based on the hydrolysis of 4-nitrophenyl acetate by carbonic anhydrases (Pocker & Stone, Biochemistry, 1967, 6, 668), with subsequent photometric determination of the dye product 4-nitrophenolate at 400 nm by means of a 96-channel spectral photometer. 2 uL of the test compounds, dissolved in DMSO (100-fold final concentration), in a concentration range of 0.03-10 umol/L (final), was pipetted as quadruplicates into the wells of a 96-hole microtiter plate. Wells that contained the solvent without test compounds were used as reference values (1. Wells without carbonic anhydrase for correction of the non-enzymatic hydrolysis of the substrate, and 2. Wells with carbonic anhydrase for determining the activity of the non-inhibited enzyme).188 uL of assay buffer (10 mmol/L of Tris/HCl, pH 7.4, 80 mmol/L of NaCl), with or without 3 units/well of carbonic anhydrase-1 [=human carbonic anhydrase-1 (Sigma, #C4396)] in order to determine carbonic anhydrase-1 inhibition or 3 units/well of carbonic anhydrase-2 [=human carbonic anhydrase-2 (Sigma, #C6165)] for measuring carbonic anhydrase-2 inhibition, was pipetted into the wells of the microtiter plate. The enzymatic reaction was started by the addition of 10 microL of the substrate solution (1 mmol/L of 4-nitrophenyl acetate (Fluka #4602), dissolved in anhydrous acetonitrile (final substrate concentration: 50 umol/L). The plate was incubated at room temperature for 15 minutes. Absorption was measured by photometry at a wavelength of 400 nm. The enzyme inhibition was calculated after the measured values were normalized to the absorption of the reactions in the wells without enzyme (=100% inhibition) and to the absorption of reactions in the wells with non-inhibited enzyme (=0% inhibition). IC50 values were determined by means of a 4 parameter fit using the company's own software. |
| Affinity data for this assay | |
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