What role does oxygen play in the reaction?

What role does oxygen play in the reaction? What would happen if there were no oxygen? of dopachrome 3. When you peel potatoes and then place them in water, they don’t turn brown. Why is this? What is missing from the enzymatic reaction? 4. Why is it important to keep the enzyme and phosphate buffer on ice? 5. Dopachrome is a precursor in the production of melanin. What is melanin and what is its function in organisms? Why do potatoes have this molecule? 6. What conclusions about enzymes in general and tyrosinase specifically can you draw from your experiment?