Final answer:
Copper and zinc-containing enzymes participate in the body's natural defenses against viral, bacterial, and parasitic infections.
Step-by-step explanation:
Copper and zinc-containing enzymes participate in the body's natural defenses against all of the above - viral infections, bacterial infections, and parasitic infections. These enzymes have antimicrobial properties and play a role in protecting the body against various types of infections. For example, copper is used in fixtures like door handles to kill microbes, while zinc chloride is commonly found in antiseptic mouthwashes to inhibit bacterial growth. These metals denature proteins, impair cell function, and therefore have strong antimicrobial properties.