1. Tyrosinase is an enzyme that catalyzes the oxidation of monophenols and catechols. This experiment uses a spectrophotometer to determine the activity of tyrosinase by measuring its oxidation of L-dopa to dopachrome over time. 2. The concentration of tyrosinase is calculated using the absorption of tyrosinase at 280 nm. Tyrosinase activity is then determined by measuring the change in absorption of dopachrome at 475 nm over 3 minutes. 3. The results show that under the conditions tested, the specific activity of tyrosinase is 82 units/mg and its rate of catalyzing L-dopa oxidation is 0.