Copper enzymes are proteins that contain copper ions as essential components for their activity. These enzymes play crucial roles in various biological processes, including oxidation-reduction reactions, which are vital for energy production and metabolism. They help in the conversion of substrates into products, facilitating important reactions in living organisms. One well-known example of a copper enzyme is cytochrome c oxidase, which is involved in the electron transport chain in mitochondria. This enzyme helps in the final step of cellular respiration, where it transfers electrons to oxygen, ultimately producing water and energy in the form of ATP.