A clear buffer solution at pH 6.8 and 0.05 mM concentration.

A homogeneous, clear L-tyrosine solution at 0.244 mM.

A ready-to-use enzyme solution at 350 U/ml in sodium phosphate buffer.

A homogeneous sample solution at 1 mg/ml concentration.

Negative control with no inhibitory effect; positive control with known inhibitory activity.

Each well contains 90 µl of the appropriate test or control solution.

Each well now contains 290 µl total volume with the substrate included.

Reaction is initiated as enzyme contacts the substrate in each well.

Absorbance values are recorded for each well (sample, negative control, and positive control).

Percentage inhibition values are obtained for each test sample and can be compared to the positive control’s inhibition result.