Question

The concentration of a purified enzyme is 10 mg/ml. Ten microlitres of the enzyme solution in a total reaction volume of 1 ml catalyses the formation of 20 nanomoles of product in one minute under optimum conditions. The specific activity of the enzyme is

Answer 1

One Unit is defined as the amount of the enzyme that produces a certain amount of enzymatic activity, that is, the amount that catalyzes the conversion of 1 micro mole of substrate per minute. A spectrophotometric assay is usually applied for this purpose by a selected substrate. Enzyme activity could be calculated using the following equation:

activity (U/L) = ((absorbance variation/time)/molar extintion coefficent * path length) * 1 micromol * (total reaction volume/total enzyme volume)