Neutrase® is an enzyme that is used to hydrolyse proteins in solution. When the enzyme is mixed with a 2% protein solution the reaction mixture changes from white to colourless. A student carried out an experiment to find the effect of copper sulfate and potassium sulfate on the activity of Neutrase®. The student made four reaction mixtures in test-tubes A to D. Test-tubes A to C contained equal volumes of protein solution and 0.1cm³ of solutions of copper sulfate or potassium sulfate. Test-tube D contained the same volume of protein solution and 0.1 cm³ of water. 0.5cm³ of a 1% Neutrase® solution was added to test-tube A and immediately placed into a colorimeter. The colorimeter was used to measure the intensity of light that is absorbed by the solution (absorbance) over 100 seconds. The procedure was repeated with the other reaction mixtures, B, C and D. The results are shown in [Figure 3.1].