Acetic Acid → 4-Nitroaniline

Participants

Reaction Steps

An inhibitor sample is dissolved in a 0.05 M Tris-hydrochloric acid buffer solution (pH=7.8) to make the total volume to 400 μl. To this solution, 50 μl of a 2 mM S-2302 solution is added and the mixture is incubated at a temperature of 37° C. for 5 minutes in a constant temperature bath. Then, 50 μl of a 0.12 unit/ml human plasma kallikrein is added and the mixture is incubated at a temperature of 37° C. for 5 minutes. Thereafter, 50 μl of 50% acetic acid is added to terminate the reaction. The absorbance of the p-nitroaniline formed in the reaction mixture is measured at 405 nm. Thus, the concentration I50 (μmol) of the inhibitor sample, at which the absorbance is one half (i.e., 1/2) of that obtained in the absence of the inhibitor sample, is determined.

Provenance & Evidence